That is a problem we all face. We profess our faith in the Lord Jesus, but at times, our actions and our words do not line up with our confession of faith.
In Luke 22:32 Jesus tells Peter, “I have prayed for you, that your faith should not fail; and when you have returned to Me, strengthen your brethren.” Peter did experience a temporary lapse of faith in Jesus, but Jesus never gave up on Peter. As we read the book of Acts and the books of 1st and 2nd Peter, we see Peter being used mightily by the Lord for His Kingdom and His glory.
This should give us hope for our lives. If we will return to Jesus, He will by no means cast us out (John 6:37). Come to Him now and receive His forgiveness for all your sins. If you have known the Lord, but have not been walking with Him, repent and receive His mercy and love. Peter was used mightily by the Lord, and I believe Jesus wants to use you to help others, to strengthen your brethren. I believe Jesus is still asking this question, “Who do you say that I am?” What is your reply?