Titus 1:5

For this cause left I thee in Crete
Not in his voyage to Rome, ( Acts 27:7 ) but rather when he came from Macedonia into Greece, ( Acts 20:2 ) . Crete is an island in the Mediterranean sea, now called Candy; (See Gill on Acts 2:11). Here Paul preached the Gospel to the conversion of many; but not having time to finish what he begun, left Titus here for that purpose:

that thou shouldest set in order the things that are wanting;
that is, form the young converts into Gospel order, into a regular Gospel church state; settle a proper discipline among them; instruct them more largely into the doctrines of the Gospel; and correct their manners, and direct them in everything, both with respect to faith and practice:

and ordain elders in every city:
for this island, though it was not above fifty miles in breadth, and two hundred and seventy in length, yet had an hundred cities in it ^F4; and it seems as if the Gospel had been preached in most, if not all of them, and churches were formed: however, in as many of them as there were churches, the apostle would have Titus see to it, and take care that they had proper officers fixed in them, particularly elders, pastors, or overseers, to preach the Gospel, and administer the ordinances to them, to watch over them in the Lord, and put the laws of Christ's house in execution, and keep up a strict discipline in it, according to the will of God. What Titus was to do in this affair, was to put the churches upon looking out, and choosing from among themselves proper persons for such service, and to direct, assist, and preside at the elections and ordinations of them: for we are not to suppose, that the ordination of elders was the sole act of Titus, or alone resided in him; but in like manner as Paul and Barnabas ordained elders in every church, by the suffrages of the people, signified by the stretching out of their hands; in which they directed, presided, and also assisted in prayer, with fasting, ( Acts 14:23 )

as I had appointed thee;
when he left him at Crete; when he gave him orders and instructions, both with respect to the persons, and their qualifications, whom he would have ordained, and with respect to the manner in which it should be done: the former of these he repeats in the following verses. From all which it clearly appears, that there were churches in Crete, and pastors placed over those churches; very probably the Cretes, who were at Jerusalem on the day of Pentecost, ( Acts 2:11 ) , and heard Peter's sermon, and were converted by him, some of them returning to their own country, might first bring the Gospel to this island, and lay the foundation of a Gospel church state here. It seems by what is said in this text, that the Apostle Paul was in this island himself, and preached the Gospel, and after him Titus, whom he left behind; and if any credit is to be given to the subscription of this epistle, he was the first bishop of the church in it: and it is certain, that in the "second" century there were churches in this island, particularly at Gortyna, and other places, to whom Dionysius ^F5, bishop of Corinth, wrote letters, in which he greatly extols Philip their bishop; and in another letter of his to the Gnossians, or to the church at Gnossus, another city in Crete, he makes mention of Pinytus as their bishop, and whom he commends for his orthodox faith, great knowledge of divine things, and care of his flock; and both these lived in the times of the Emperors Antoninus Verus and Commodus ^F6; which churches, no doubt, continued in the "third" century, since in the "fourth" we read of bishops sent from Crete to the synod at Sardica: and in the "fifth" century, a bishop of Gortyna in Crete is reckoned among the bishops in the council of Chalcedon: and in the "sixth" century, Theodorus, bishop of the same place, subscribed in the fifth synod at Constantinople: and in the "seventh" century, Paul archbishop of Crete, Basil bishop of Gortyna, with several other bishops of churches in the island, were present at the sixth synod at Constantinople: and in the "eighth" century, as appears from the acts of the Nicene synod, Helias was bishop of Crete, Anastasius bishop of Gnossus, a city in it, and Melito, Leontins, and Galatas, bishops of other places in the same island: and in the "ninth" century, a bishop of Gortyna, in defence of the cause of Christ, became a martyr ^F7; so far churches, and bishops, bearing the Christian name, are to be traced in this island.