Genesis 15:6

The Bible says that Abram believed the Lord, and the Lord accounted it to him for righteousness.  He was not declared righteous by his works, but by his faith.  This is the first reference in the Bible to Abram’s faith.  Someone has even said that this is the Old Testament equivalent to John 3:16 in the New Testament.  We are saved by simply believing in Christ.  The Hebrew word translated ‘believed’ means to lean your whole weight upon, or to lean into.  When the Bible says that Abram believed in the Lord, it means that he leaned wholly upon the Lord and His promise.  He placed all of his confidence in God.  He wasn’t declared righteous because of his works, but because of his faith.  We are not saved by making promises to God, but by believing the promises of God.  Abram’s faith will later be seen through his obedience.  The fact that he would offer Isaac on the altar of submission is further evidence of his faith.  For this reason, Abram is described as being the father of the faithful.  Paul uses him as an example in Romans 4:1-3 to describe how sinners are justified by faith in Christ, not their works.  

Without faith, it is impossible to please God.  The one who desires to be saved must realize that faith in Christ alone is the answer.  Just as Abram believed in the Lord and it was accounted it to him for righteousness, so also must you believe in Christ in order to be made righteous.  Just as Abram believed the promise of God, so also must you believe the promise of God in Christ.

For more, read Romans 4:1-25