Peter had a hard time growing up in the faith.  As a Jew, he had a lifetime of learning to obey hundreds and hundreds of Jewish law.  After Christ arose, Peter understood that Jesus was the Messiah.  But the idea of God including everyone in his plan of salvation was foreign to Peter.  He couldn't imagine that Jesus came to save Gentiles.  He wasn't alone.  There is some indication that James seemed to think that you had to become a Jew before you could be a Christian as well.

You remember that God let a blanket come down with all kinds of forbidden meat in it and told Peter that he was to eat.  Peter refused because some of the animals were forbidden under Jewish law.  God told him, "...what God has cleansed, don't you call common."  Three times.  God had changed everything with the sacrifice of his son.   Peter finally got it, did what God said, and went to share Christ with a Roman Centurion.  A Gentile.  You would think that would be the end of it.  But, no.  It wasn't.  Peter still had a problem with Gentiles being as good as Jews.

When Paul found Christ as his Savior (on the road to Damascus) he went to Jerusalem to meet James, John and Peter who were looked upon in the church as leaders.  They were afraid of Paul, because Paul had been killing Christians.  Barnabas interceded and assured them that Paul was indeed preaching Christ to the Gentiles. They compared notes and agreed that they were all on the same page as far as the truth of the gospel was concerned.  Christ, and Christ alone saved you.

But fourteen years later, Paul returned to Jerusalem because of a conflict that he had with Peter's behavior when Peter had visited Antioch.  Paul  condemned Peter for his hypocrisy, and implicated James and the others as well.  They had a conference and finally,  after fourteen years, Paul, Peter, James and John got their ducks in a row concerning the necessity of obeying Jewish law.  Galations 2: 1-21.  Please read the chapter.  It shows the total humanity of a group of men who were trying to do God's work.  And settled the issue of salvation for Gentiles.  The gospel was for everyone.

There is hope for you and me.  If apostles could fail and admit their faults and be forgiven, so can you and I.  Thank goodness.