None of us judge Peter for speaking out of fear when he denied Jesus on the night He was betrayed! That night EVERYONE denied Jesus! His denial was evidence of his humanity and failure. His confession and repentance was the true evidence of his heart. Peter's denial of Jesus was certainly a shameful event in his life. Denying Jesus was NOT the pattern of his life.
Unfortunately, people tend to use other's failures to excuse their own habits. To say that everyone has failures is a fact. To use another's failure to excuse our behavior is foolish. Who we are is seen in the patterns of our lives, not in the snapshots of our victories or our failures.
Live for Jesus. It begins with faith. There will be failures. But the pattern of our life is to reflect our trust in Him.