Two american jewish men send their sons to Jerusalem to learn about their culture.

A year later the two are having a chat:

-- I am so disappointed in my son, I don't know what to do... Once he returned, he claimed to have become christian!

-- My son as well, this is a tragedy.

-- We should go see our Rabbi, maybe he can guide us.

The two then visit the Rabbi and tell him their stories, to which he replies:

-- Unfortunately, I'm in the same boat as you two. I sent my son to Jerusalem a few years ago and he also became christian. Only God can help us now, we should pray to him!!!

So they start praying:

-- Please help us God, we sent our sons to Jerusalem so they could learn about our culture, but instead they returned as christians!!!

God thinks for a while and says:

-- You guys won't believe, but 2000 years ago I too sent my son to Jerusalem...