Then what did Jesus mean in John 3:3?
"Jesus answered and said to him, “Most assuredly, I say to you, unless one is born again, he cannot see the kingdom of God.”
You are born again by the Sacrament of Baptism.
But the early Christians uniformly identified this verse with baptism. Water baptism is the way, they said, that we are born again and receive new life—a fact that is supported elsewhere in Scripture (Rom. 6:3–4; Col. 2:12–13; Titus 3:5). No Church Father referred to John 3:5 as anything other than water baptism.
Yes. When baptized the first time. God doesn’t make me mistakes and said, “Oppsie. Get baptized again”. That’s ridiculous and devil talk.