"He did not consult us when He invented sex: He has not consulted us either when He invented this."

Public Domain"Christ Talking with Nicodemus at Night," Crijn Hendricksz. Volmarijn (1616-45)
Lewis is talking about being "born again." Christ used the term in speaking to Nicodemus in John 3:3-8.

Jesus answered him, "Truly, truly, I say to you, unless one is born again he cannot see the kingdom of God." Nicodemus said to 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, "Truly, truly, I say to you, unless one is born of water and the Spirit, he cannot enter the kingdom of God. That which is born of the flesh is flesh, and that which is born of the Spirit is spirit. Do not marvel that I said to you, 'You must be born again.' The wind blows where it wishes, and you hear its sound, but you do not know where it comes from or where it goes. So it is with everyone who is born of the Spirit."