Also, certainly, Abraham himself was strengthened in his faith through this episode. When we pass the tests of God, we ourselves are strengthened in our faith as a result. Abraham's actions were actually a fulfillment of the Bible's assertion that Abraham had faith. The Bible could merely have stated that Abraham had faith, but we would not have known the extent of his faith unless we were shown his deeds. In fact, Abraham is considered a great man of faith, not because the Bible says that he had faith, but because his faith was demonstrated and fulfilled through his testing.
Untested faith is unproven faith.
James looks at the effect of his justification, which was the act that fulfilled the statement that Abraham had faith in the promise. Abraham's test specifically referred to his faith in the earlier promise. If Abraham truly believed that his offspring through Isaac would be as the stars in the sky, he would have no problem with offering Isaac to the Lord, since it was the Lord Himself who made the original promise. This supposed discrepancy can be resolved by studying the purpose and context of Paul's and James' statements. James' final example is Rahab, whose history is found in Joshua 2.