James 2:14-26
14 What use is it, my brethren, if a man says he has faith, but he has no works? Can that faith save him? 15 If a brother or sister is without clothing and in need of daily food, 16 and one of you says to them, "Go in peace, be warmed and be filled," and yet you do not give them what is necessary for their body, what use is that? 17 Even so faith, if it has no works, is dead, being by itself. 18 But someone may well say, "You have faith, and I have works; show me your faith without the works, and I will show you my faith by my works." 19 You believe that God is one. You do well; the demons also believe, and shudder. 20 But are you willing to recognize, you foolish fellow, that faith without works is useless? 21 Was not Abraham our father justified by works, when he offered up Isaac his son on the altar? 22 You see that faith was working with his works, and as a result of the works, faith was perfected; 23 and the Scripture was fulfilled which says, "And Abraham believed God, and it was reckoned to him as righteousness," and he was called the friend of God. 24 You see that a man is justified by works, and not by faith alone. 25 And in the same way was not Rahab the harlot also justified by works, when she received the messengers and sent them out by another way? 26 For just as the body without the spirit is dead, so also faith without works is dead. NAS
Now put James teaching in context and it is summerized in verse 26. James is not teaching that works are necessary for faith and salvation but good works are an outworking of faith and salvation. Good works is what brings faith to fullness not the other way around. What justified Abraham? His willingness to sacrifice the son God promised would be the line through which the Messiah would come or his faith that God could raise a dead son to life? What justified Abraham the work of performing a sacrifice or his faith in a resurrecting God? The answer is obvious his faith in God.