Theology Overview


Theology Overview

The word doctrine means “teaching” or “instruction.” Applied to the study of the Scriptures, another word for doctrine is “truth,” the gathering together in a systematic way of all that God’s infallible, inerrant Word says about a given subject.

While the Bible contains all the truth God wants us to know about himself, these teachings are not arranged in an alphabetic, systematic way because the Bible is not a textbook. The challenge is to organize the truths of God’s Word in a way that clearly communicates what the Bible teaches on any subject it addresses. This process is called systematic theology and is needed because we cannot turn to any one portion of Scripture to find the full biblical revelation on any subject. So it’s important to bring together the Bible’s teachings on any doctrine so that they can be studied in an orderly way.

This is the purpose of this section, which summarizes the major doctrines of systematic theology. I have dealt with this at length in my Understanding God series (Moody Publishers) and in detail in my book, Theology You Can Count On (Moody, 2008).

Theology Proper

Virtually all studies on theology begin with this subject, which is so-called because it focuses on God the Father. These truths will help you grasp the greatness of our God. (See the Doctrinal Outlines for more detail.)

1. God is an eternal, transcendent being. God has no beginning or end (Ps 90:1-2). He told Moses, “I AM WHO I AM” (Exod 3:14). God exists prior to, above, and distinct from his creation (Isa 40:18-25). God is distinct in his person (Ps 50:21) and in his thoughts (Isa 55:8-9).

2. God is a spirit being. God in his essence is pure spirit (John 4:23-24a). He is immaterial in that he does not have a body; therefore, God is invisible (John 1:18).

3. God is an immutable being. Immutability means not having the ability to change. God cannot, does not, and will not change (Num 23:19; Mal 3:6), either in his person or in his purposes, although he can and does change in his methods. Therefore, we can trust his promises and eternal love for us (Jer 31:3; Jas 1:17).

4. God is a triune being. The Bible makes it inextricably clear that there is only one true God, and he is one (Deut 6:4; Isa 45:5; 1 Cor 8:4). However, this one God exists in three co-eternal and co-equal—yet distinct—persons: Father, Son, and Holy Spirit. They are unified in their essence, yet each has a different function in the Godhead.

We use the words Trinity or Triune to speak of the unity of this three-in-one God, although these words themselves do not appear in Scripture. But the truth of the divine Trinity appears throughout the Bible. In Matt 28:18-20, Jesus used the singular “name” of the Father, Son, and Holy Spirit, a strong proof of both the unity and the “threeness” of God.

The Trinitarian nature of God is also demonstrated in that the Father (Gal 1:1, 3; Eph 1:2-3), the Son (John 20:28), and the Holy Spirit (Acts 5:3-4) are each called God.


Christology consists of what the Bible teaches about Jesus Christ in his person and work. (See further under “Christology” in the Doctrinal Outlines.) Jesus is unique, the only “one-of-a-kind” Son of God (John 3:16) who is both fully God and man, perfect in both natures without any mixture, division, or confusion.

Jesus made a clear claim to his pre-existence and divine nature as God (John 10:30), a statement his hearers understood so well that they tried to stone him for making himself equal with God (10:33). The prophecy of his birth also included a claim to his eternal existence (Mic 5:2). Isaiah called Jesus Christ “Eternal Father” or “Father of eternity” (Isa 9:6).

Fully divine, Jesus also became a man in his birth, or incarnation. He was born as no other person has been born, because he was born of a virgin (Isa 7:14; 9:6; Matt 1:22-23). The apostle Paul tied these prophecies together in Gal 4:4. Jesus is also unique in his death and resurrection.


The formal name for study of the person and ministry of the Holy Spirit is derived from the Greek word pneuma, which means “breath” or “spirit.” He is the Third Person of the Trinity, co-equal and co-eternal with the Father and Son. (See the Doctrinal Outlines for more detail.)

The Holy Spirit’s unique role is to make the truth of God’s Word and the reality of his presence a living experience in the lives of Christians. The Spirit is active on every page of Scripture, from his work in creation (Gen 1:2) to his invitation to salvation and eternity with Jesus in heaven (Rev 22:17).

Two of the Holy Spirit’s most important ministries have already been accomplished. He was the life-giving force in Jesus’s virgin birth (Luke 1:35), protecting the Savior from the contamination of human sin inherited through one’s father. The Spirit inspired the writers of God’s Word so that what was written is infallible, inerrant, and wholly trustworthy, protected from human contamination (1 Pet 1:20-21).

The Holy Spirit’s primary roles today include glorifying Christ (John 16:14), indwelling believers for the power to do what God has called us to do (Acts 1:8), and convicting unbelievers of their sin and coming judgment (John 16:7-11).


Salvation is the miracle by which a lost person is granted forgiveness and given eternal life through the death and resurrection of Christ. The term soteriology comes from the Greek word soter, which means “savior.”

1. Sin: the need for salvation. The Bible declares that all of us are under the curse and penalty of sin (Rom 3:23; 6:23) because we have failed to measure up to God’s demands of perfection. We inherited a sin nature from Adam (Rom 5:12). Our sin debt is so great , we cannot pay it ourselves which is why the sinless Son of God had to die for our sins on the cross.

2. Justification: the verdict of salvation. The Greek word translated “justify” means to announce a favorable verdict in a courtroom, or to declare righteous. Justification is a judicial act by which God declares righteous those who believe in Jesus Christ. The Bible is clear that justification comes from God alone, for “God is the one who justifies” (Rom 8:33). Every person ever born is lost in sin and needs to be justified through Christ’s redemptive sacrifice (Rom 3:23-24). Justification is a gift of God’s grace. We have nothing to offer God to make us acceptable to him.

3. Regeneration: the miracle of salvation. Regeneration is the process by which God implants new spiritual life, his very life, in the heart of a sinner who believes on Jesus Christ for salvation. The Bible describes regeneration as a new birth (John 3:1-8), a spiritual resurrection (Rom 6:4-5), and a new creation (2 Cor 5:17). Salvation not only brings such a complete change that we are born again spiritually and raised from the dead, but we are also completely remade people.

4. Security: the assurance of salvation. Our assurance of salvation is bound up in the promise of the gospel and the finished work of Christ (John 5:24; 10:27-30). John built a powerful case for our security (1 John 5:11-13), concluding with this assuring statement: “I have written these things to you who believe in the name of the Son of God so that you may know that you have eternal life” (5:13).

There is certainty in our salvation. Jesus never brought anyone from spiritual death to eternal life only to let that person fall back under God’s judgment.


This doctrine involves the study of God’s Word. The Bible is unique among all other books and so-called sacred writings, because it alone is the very Word of God (Isa 55:10-11).

1. The Bible is truth. God’s Word is pure, unadulterated truth (Ps 12:6). God declares that when he speaks, everything he says is true (Isa 45:19). Jesus also affirmed the absolute truth of Scripture (John 17:17).

2. The Bible is authoritative. Christ said that the Bible carries the imprint of his divine authority (Matt 24:35). The authority of God’s Word is a settled issue in heaven (Ps 119:89).

3. The Bible is Holy Spirit-inspired: The Spirit inspired the writing of Scripture to protect it from contamination by human ideas or opinions (2 Pet 1:20-21). So it is accurate to say that God himself is the author of the Bible, and the result is pure truth from him.


The doctrine of the church comes from the Greek word ekklesia, which means “assembly” or “called out ones.” From this term we can formulate a definition of the church as a special called-out assembly of people, chosen by God to become part of what Paul called both the body and the bride of Christ (1 Cor 12:12-31; Eph 5:22-27, 32). The Bible also makes it clear that the church is God’s family (Rom 1:13; 16:1; Heb 2:11). Thus, the church consists of people; it is not merely an organization or a building.

The church is the most important entity on earth in terms of God’s program for this age. God has commissioned the church alone to be his representative agency. And the church alone has been granted the authority to bring the realities of God’s kingdom program to bear on history since it has been given the keys of the kingdom (i.e., heavenly authority to be utilized on earth, Matt 16:18-19).

Jesus prophesied the coming of the church during a critically important time of teaching with the apostles (Matt 16:13-19). This passage is unmistakably clear that the church is built on Christ, not Peter or any other apostle. Jesus said it is “my church.” Both Paul and Peter agreed that Christ alone is the church’s “cornerstone” (Eph 2:20; 1 Pet 2:6).

The universal church is made up of all believers from the church’s birthday at Pentecost (Acts 2) to the future day when Christ will rapture his church (1 Thess 4:13-18) from the world. But the universal church is visibly expressed and functions through the many local churches where believers assemble to carry out the mandates Christ gave to his people and live out the principles of the Christian life.

The church is the apex of God’s eternal plan for mankind (Eph 3:1-21). It is the means by which God will demonstrate to the angelic realm—including both holy angels and Satan and his demons—his infinite wisdom in choosing weak, lesser creatures like us to manifest his glory and carry out his kingdom program.


This doctrine deals with angelic beings, both the holy (elect) angels and the evil ones (Satan and his demonic realm). Angels are not eternal but were created by God as part of his original creation (Col 1:16). This verse also teaches the important truth that angels were not created for themselves, but for Christ and for God’s divine purposes. Angels were created to give God endless worship around his throne (Ps 148:2). This is important because a heresy that arose in the early church was the worship of angels (Col 2:18). Although angels are far more glorious and powerful than human beings, they were also created to be “ministering spirits” (Heb 1:14) to serve God and his people.

Angels are spirit beings, although they can take on a human appearance in order to accomplish a specific, God-given mission on earth. An example of this is when the angels visited Abraham and destroyed Sodom (Genesis 18-19; see also Heb 13:2). The word angel means “messenger,” which provides a basic understanding of their ministry. As God’s creation, angels also possess intellect, emotion, and will—the fundamental attributes of personhood.

Since angels do not reproduce (Mark 12:25) and do not die, the number of angels God created is the same number of those who exist now. We aren’t told their numbers, but they are said to exist in unimaginable numbers (Deut 33:2; Rev 5:11).

The first category of angels are those called holy who stayed true to God and did not follow Satan in his rebellion. Satan, formerly known as Lucifer (Isa 14:12, KJV) or “morning star,” heads the second category, the evil angels known as demons. This includes one-third of the angels who followed Lucifer when he tried to usurp God’s throne because he wanted to be worshiped as God (Rev 12:4) and build his own demonic kingdom to rival the righteous kingdom of God (Isa 14:13-14; Col 1:13).

Satan’s evil character was formed the moment his pride led him to rebel against God and seek to establish his own kingdom (Isa 14:12-15). He was transformed from the most beautiful of all God’s creatures into the prince of darkness, kicked out of heaven to earth, falling with the speed of lightning (Luke 10:18).

Lucifer was also given some new names. Satan means “adversary, opposer.” Devil means “accuser” or “slanderer.” He was defeated the moment he challenged God, was defeated again at the cross (Col 2:15), will one day be confined during Christ’s millennial reign, and then judged and sent forever to hell (Matt 25:41, Rev 20: 7-10).

In the meantime, Satan and his demons have access to earth to deceive the world and carry out spiritual warfare against believers (Eph 6:10-12). Satan has also been granted temporary access to heaven, to accuse believers before God (Job 1:6; 2:1-2). But Jesus is our defense attorney to counter those accusations with his blood (1 John 2:2).


The study of Bible prophecy is so-named because it is derived from a compound of two Greek words meaning “last things.” It’s astounding to realize that God has chosen to reveal his plan for the future ahead of time—not to satisfy our curiosity or so we can guess at dates for Christ’s return, but as a stimulus to holy living (2 Pet 3:1-15). The Scriptures set forth several major events that are yet to come on God’s prophetic timetable:

1. The rapture of the church. The rapture will be instantaneous and could occur at any moment. It will end the church age as Christ comes in the clouds to take his church home to be with him (1 Thess 4:13-18). This is the “blessed hope” we look forward to as God’s people (Titus 2:13). After the rapture, believers will appear before the judgment seat of Christ to receive or lose rewards based on their faithfulness or lack thereof (2 Cor 5:10).

2. The tribulation. The joy of the rapture for believers will usher in a time of unprecedented judgment, terror, and suffering on the unbelieving world left behind, as the Antichrist and his false prophet take center stage.

Jesus prophesied the tribulation (Matt 24:4-28), and the book of Revelation (particularly chapters 4–18) chronicles its unfolding. Although this seven-year period will begin peacefully as the Antichrist makes a peace treaty with Israel, at the midpoint he will break this treaty and reveal himself in all of his evil. The second half of the tribulation will be a literal “hell on earth” for those who have to endure it.

3. Christ’s second coming and millennial kingdom. At his triumphant return, Christ will defeat Satan, the Antichrist, and all the forces of evil (Rev 19:11-21). He will then bind Satan and establish his glorious one-thousand-year reign on the throne in Jerusalem as Israel’s Messiah (Rev 20:1-2).

4. The great white throne judgment and the eternal state. The great white throne judgment (Rev 20:11-15) is the last event before God brings in the eternal state. This is a judgment for those who have rejected Christ. Their eternal doom is announced and carried out. But for believers, our judgment for sin is past and the bliss of our eternal life in heaven is described in Revelation 21–22. We will forever be with the Lord.

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