'Enter' in the Bible

Nicodemus saith unto him, How can a man be born when he is old? can he enter a second time into his mother's womb, and be born?

Jesus answered, Verily, verily, I say unto thee, Except one be born of water and the Spirit, he cannot enter into the kingdom of God!

I am the door; by me if any man enter in, he shall be saved, and shall go in and go out, and shall find pasture.