Even as Abraham believed God, and it was accounted to him for righteousness.
The answer to Galatians 3:5 is here taken for granted, It was by the hearing of faith: following this up, he says, "Even as Abraham believed," etc. (Genesis 15:4-6; Romans 4:3.) God supplies unto you the Spirit as the result of faith, not works, just as Abraham obtained justification by faith, not by works (Galatians 3:6; Galatians 3:8; Galatians 3:16; Galatians 4:22; Galatians 4:26; Galatians 4:28). Where justification is, there the Spirit is, so that if the former comes by faith, the latter must also.
It - his believing.
Accounted - `reckoned.'