Wherefore (oqen). Old relative adverb (o and enclitic qen, whence of place ( Matthew 12:44 ), of source ( 1 John 2:18 ), of cause as here and often in Hebrews ( 1 John 3:1 ; 1 John 7:25 ; 1 John 8:3 ; 1 John 9:18 ; 1 John 11:19 ). It behoved him (wpeilen). Imperfect active of opeilw, old verb to owe, money ( Matthew 18:28 ), service and love ( Romans 13:8 ), duty or obligation as here and often in N.T. ( Luke 17:10 ). Jesus is here the subject and the reference is to the incarnation. Having undertaken the work of redemption ( John 3:16 ), voluntarily ( John 10:17 ), Jesus was under obligation to be properly equipped for that priestly service and sacrifice. In all things (kata panta). Except yielding to sin ( Hebrews 4:15 ) and yet he knew what temptation was, difficult as it may be for us to comprehend that in the Son of God who is also the Son of man ( Mark 1:13 ). Jesus fought through to victory over Satan. To be made like unto his brethren (toi adelpoi omoiwqhnai). First aorist passive infinitive of omoiow, old and common verb from omoio (like), as in Matthew 6:8 , with the associative instrumental case as here. Christ, our Elder Brother, resembles us in reality ( Philippians 2:7 "in the likeness of men") as we shall resemble him in the end ( Romans 8:29 "first-born among many brethren"; 1 John 3:2 "like him"), where the same root is used as here (oiwma, omoio). That he might be (ina genhtai). Purpose clause with ina and the second aorist middle subjunctive of ginomai, to become, "that he might become." That was only possible by being like his brethren in actual human nature. Merciful and faithful high priest (elehmwn kai pisto arciereu). The sudden use of arciereu here for Jesus has been anticipated by 1 John 1:3 ; 1 John 2:9 and see 1 John 3:1 . Jesus as the priest-victim is the chief topic of the Epistle. These two adjectives (elehmwn and pisto) touch the chief points in the function of the high priest ( 1 John 5:1-10 ), sympathy and fidelity to God. The Sadducean high priests (Annas and Caiaphas) were political and ecclesiastical tools and puppets out of sympathy with the people and chosen by Rome. In things pertaining to God (ta pro ton qeon). The adverbial accusative of the article is a common idiom. See the very idiom ta pro ton qeon in Exodus 18:19 ; Romans 15:17 . This use of pro we had already in Hebrews 1:7 . On the day of atonement the high priest entered the holy of holies and officiated in behalf of the people. To make propitiation for (ei to ilaskesqai). Purpose clause with ei to and the infinitive (common Greek idiom), here present indirect middle of ilaskomai, to render propitious to oneself (from ilao, Attic ilew, gracious). This idea occurs in the LXX ( Psalms 65:3 ), but only here in N.T., though in Luke 18:13 the passive form (ilasqhti) occurs as in 2 Kings 5:18 . In 1 John 2:2 we have ilasmo used of Christ (cf. Hebrews 7:25 ). The inscriptions illustrate the meaning in Hebrews 2:17 as well as the LXX.