"Fonda claimed to have become a Christian." Babylonian Mystics believe Christ was one of the greatest spiritual leaders. Today they base that on the Gospel of Thomas that never made it to the bible and they believe was hidden by the church.
Thomas which isn't in the bible. 80% of it was found in Nag Hammadi Codex II 1945. Specifically some of conversations with Simon peter. Though gnosticism always believed Jesus was a Gnostic.
https://www.gospels.net/thomas This Video explains the little information prior to 1945. Church seemed to know of Thomas but said it was not authentic and held most of it.
https://www.youtube.com/watch?v=lh3cTTV9s-c