One must be born agaion according to John 3:5-8
5 Jesus answered, “Most assuredly, I say to you, unless one is born of water and the Spirit, he cannot enter the kingdom of God.
6 That which is born of the flesh is flesh, and that which is born of the Spirit is spirit.
7 Do not marvel that I said to you, ‘You must be born again.’
8 The wind blows where it wishes, and you hear the sound of it, but cannot tell where it comes from and where it goes. So is everyone who is born of the Spirit.”
9 Nicodemus answered and said to Him, “How can these things be?”
10 Jesus answered and said to him, “Are you the teacher of Israel, and do not know these things?
11 Most assuredly, I say to you, We speak what We know and testify what We have seen, and you do not receive Our witness.
12 If I have told you earthly things and you do not believe, how will you believe if I tell you heavenly things?
13 No one has ascended to heaven but He who came down from heaven, that is, the Son of Man who is in heaven.
14 And as Moses lifted up the serpent in the wilderness, even so must the Son of Man be lifted up,
15 that whoever believes in Him should not perish but have eternal life.
16 For God so loved the world that He gave His only begotten Son, that whoever believes in Him should not perish but have everlasting life.
No one is a Christian from birth because we have a sinful nature and that is of the natural man.