I have heard it said often; "The question is, how much can you get wrong and still be a Christian?" That seems like a logical question, because we all get something wrong. I'll be the first to admit that I am wrong about a GREAT many things. Thanks be to God my trust is not in myself, but solely in the only One who is right, Christ Jesus, the Son of the living God.
Protestants say Catholics are not saved and Catholics say Protestants are not saved. Even within Protestantism there is much yammering. I cannot look at social media without seeing someone proclaim someone else as being hell bond. It seems that if you don't meet up to the expectations of someone else's brand of Christianity you are dammed.
I think the better question to ask is what must you get right? In Matthew chapter 16 there was much talk among the crowds as to Who or Whom they thought Jesus was. Jesus asked His disciples who they thought He was.
"Simon Peter answered, “You are the Christ, the Son of the living God.” And Jesus said to him, “Blessed are you, Simon Barjona, because flesh and blood did not reveal this to you, but My Father who is in heaven. I also say to you that you are Peter, and upon this rock I will build My church; and the gates of Hades will not overpower it. I will give you the keys of the kingdom of heaven; and whatever you bind on earth shall have been bound in heaven, and whatever you loose on earth shall have been loosed in heaven.” Then He warned the disciples that they should tell no one that He was the Christ." (Vs. 16-20).
Peter came to Christ on the water, but after becoming frightened he began to sink (Mat.14.30).
Peter rebuked the Lord when He told His disciples what was going to happen to Him in Jerusalem (Mat.16.22).
Peter began speaking at the transfiguration when he should have been silent and worshiped (Mat.17.4).
Peter said that he would not deny the Lord but did exactly that three consecutive times (Mat.26.33,35,74).
The Lord was grieved and asked Peter to stay up with Him but Peter slept (Mat.26.40).
Peter was rebuked by Paul for caring what men thought of him if someone were to see him eating with Gentiles. (Gal.2.11,12)
In all Peter got many things wrong, but he got the one thing right that he needed to get right. He believed that Jesus is the Christ, the Son of the living God. Jesus promised eternal life not to the one who is perfect, but to the one who believes in Him (John.11.25-27).