Now the just shall live by faith: but if any man draw back, my soul shall have no pleasure in him.
Just. 'Aleph (') A, Vulgate, read 'MY just man.' God is the speaker-`He who is just in my sight.' Bengel, with Delta f, 'The just shall live by MY faith.' So the Hebrew, Habakkuk 2:4, literally, 'The just shall live by the faith of Him'-namely, Christ, the final subject of "the vision," who 'will not lie;' i:e., disappoint. Here not merely the beginning, as in Galatians 3:11, but the continuance of the spiritual life of the justified man is referred to, as opposed to apostasy. In Romans 1:17 the righteousness or justice of God in the Gospel plan is what is dwelt on; so the emphasis falls on "just." In Galatians 3:11 the emphasis is on "faith" as the means of justificaton. Here, the emphasis is on "live." As the justified man receives first spiritual life by faith, so it is by faith that he shall continue to live (Luke 4:4). Faith here is that fully-developed living trust in the unseen (Hebrews 11:1) Saviour, which keeps men stedfast amidst persecutions and temptations (Hebrews 10:34-36).
But - Greek, 'and.'
If any man draw back. The Greek admits Alford's, 'if he (the just man) draw back.' This would not disprove the final perseverance of saints: for 'the just man' in this latter clause would mean one seemingly, and in part really, though not savingly, "just;" as in Ezekiel 18:24; Ezekiel 18:26. In the Hebrew this latter half stands first. Therefore 'and' (not "but"), in Paul, merely joins his two quotations: the 'drawer back' answering to the 'lifted-up soul' must, if Paul follows Habakkuk (Hebrews 2:4, note), be distinct from "the just;" for the former stands first, and refers to the Chaldean, or else the unbelieving Jews. "Behold, his soul which is lifted up is not upright in him." Habakkuk states the cause of drawing back: a soul lifted up by prosperity, like the Chaldean, in self-inflated unbelief setting itself up against God. Paul, by the Spirit, states the effect: it draws back. What in Habakkuk is, "his soul ... is not upright in him," is in Paul, "my soul shall have no pleasure in him." Habakkuk states the cause, Paul the effect: He who is not right in his own soul does not stand right with God; God has no pleasure in him. Bengel translates Habakkuk, 'His soul is not upright in respect to him'-namely, Christ, the subject of "the vision;" i:e., Christ has no pleasure in him (cf. Hebrews 12:25). Every flower in spring is not a fruit in autumn.