In his letter to the Romans, the apostle Paul declares that Scripture proves Abraham wasn’t justified by God on account of anything he did or accomplished. That is why Paul claims that he had nothing to boast about before God. His obedience was not a factor in his justification. Abraham simply believed what God promised, and so God credited him with righteousness.
Now, we have to be careful here. Righteousness is not credited to us for believing in God or in a God that saves. We can have a strong faith in the existence of God. We can believe that the Bible is God’s holy word. We can show great reverence for God but at the same time, still be seeking to save and justify ourselves by trusting in our own moral performance or character. Righteousness is only credited to us when we transfer our trust from anything else in life to a complete trust in who God is and what He says He will do. True saving faith is a “trust-transfer.”
We must not even place our trust in our act of believing. Adding one ounce of confidence in our own moral achievements or character for justification reveals self-trust which is failure to believe the gospel. It is failing to believe God.
God has promised that Jesus’ life and death has paid the penalty for our sins in full and has granted us a righteous standing before Him in spite of our sinfulness. Justification is guaranteed to anyone and everyone who believes this promise made by God. Yet, the simplicity of this gospel is a stumbling block to the religious and foolishness to the irreligious.
Our greatest temptation is failing to believe the cross was necessary (irreligion) or failing to believe that it was all that was needed (religion).