The answer
Doubt is lack of faith and is definitely a sin. Abraham sinned by doubting God not waiting on His promise. We should not say that faith grows through doubt; but through temptations and repentance we get closer to God. When St. Peter doubted while walking on the water, he began to sink and the Lord rebuked him saying "O you of little faith, why did you doubt" (Mt 14:31). A righteous person learns from his mistakes, identifies them and repents. Abraham is not called the friend of God because he doubted but because of his faith and righteousness "by faith Abraham obeyed when he was called to go out to the place which he would receive as an inheritance. And he went out, not knowing where he was going. By faith he dwelt in the land of promise as in a foreign country" (Heb 11:8-9). The Holy Bible says about King David "the Lord has sought for Himself a man after His own heart" (1 Sam 13:14). Although we know that David sinned against the Lord, but it is his wholehearted repentance which made him deserve this attribute.Answered by His Eminence Metropolitan Youssef (opens in a new tab)