"When Abram was ninety-nine years old, the LORD appeared to Abram and said to him, 'I am Almighty God; walk before Me and be blameless. . . . ' "
How is a man to be "blameless" before God? Does this mean that he will never sin again? No. Abram (later Abraham) was blameless in the Object of his faith (the Lord Jesus Christ). Blamelessness in the Bible implies sincerity and wholeheartedness--not sinless perfection (nor trying real hard in the flesh's efforts).
As Abraham "walked" with God, he gained more and more confidence all the time. The same is true for every sincere churchman today.
[Puritan quote of the day: "When do you expect that it will be more likely that you should be awakened and wrought upon than now?"
--Jonathan Edwards, from his sermon, "Pressing into the Kingdom of God"]