Was Abraham justified before God because of his great faith and accomplishments?
No. Abraham was not justified before God by his accomplishments or works. Romans 4:2 says if Abraham were justified by works, he would have reason to glory, but never before God. His justification was faith plus nothing; even while waiting, he failed miserably.
Les explains that God does not use gifted, wealthy, or intelligent human beings because they would brag. The same applies to Abraham: though he was a great man of faith who waited years for the promises, it was faith plus nothing. It was not that Abraham had accomplished so much or was such a great individual. Romans 4:2 says that if Abraham were justified by works—by what he could accomplish or earn—then he would have reason to glory, but never before God. No one will brag to God, 'Look what I've done,' and God would not allow even Abraham to do so. In fact, while waiting, Abraham failed miserably and fell flat on his face.