Depends. We can leave aside groups like “Jews for Jesus” who were founded to deliberately use deception and fraud in order to trick vulnerable and lonely Jews into becoming Christians. Even with that aside, there already was a movement for Jews (or anybody else) to become Christians, and it’s named Christianity.
Of course, the rub was:
The example of Jesus’ followers might show how effective they were at keeping Jewish customs. 
I’d also add that, sooner or later, it’s pretty much inevitable. Hence, even secret Jews in Spain whose descendants no longer know they’re Jews. Or people who identify as “German” or “Irish” or what have you, as 3rd generation Americans, who would be told “No, you’re just an American” by native Germans and Irish folks.
And the answer would be that religiously he’d placed himself firmly outside of Judaism and that, essentially, he’d left the tribe. His children would be brought up as Christians, and that was the culture he’d chosen for himself and his family.
He might very well be used to, even able to fit into Jewish culture, but he’s no longer a Jew in any real sense. He’s become a “Christian who has Jewish heritage.” There is, really, no difference between him and a gentile who grew up around Jews and can sling the lingo.
Sure they do.
Likewise, I want to have Jeri Ryan be my personal love Goddess on alternating weekends.
I’m rooting for myself, by the way.
