Justification has always only been by faith. While it is true that Abraham believed God, so he was justified (Genesis 15:6), it is also true that he believed God, so he obeyed God's command to offer Isaac (Hebrews 11:17), so the same faith by which he was justified was also expressed by being an obeyer of God, but he did not earn his justification as the result of his obedience (Romans 4:1-5). In James 2:21-24, it quotes Genesis 15:6 to support saying that Abraham was justified by his works when he offered Isaac, that his faith was active along with his works, and his faith completed his works, so he was justified by his works insofar as they were expressing his faith, but not insofar as they were earning a wage. While Paul denied that was can earn our justification as wage (Romans 4:1-5), he also said that only the doers of the law will be justified (Romans 2:13), so there must be a reason why our justification requires us to choose to be doers of the law other than in order to earn it as a wage, namely faith insofar as the same faith by which we are justified does not abolish our need to be doers of the law, but rather our faith upholds it. Another way to put it is that we become someone who has faith, someone who is a doer of the law, and someone who will be justified all at the same time and anyone who is not one is also not the others, but we do not earn our justification as the result of being a doer of the law. In Titus 2:14, Jesus gave himself to redeem us from all lawlessness and to purify for himself a people of his own possession who are zealous for doing good works, so becoming zealous for being a doer of good works in obedience to God's law is the way to believe in what Jesus accomplished through the cross and the way to become justified through faith.