Yes it does have to do with Christianity very much so as it's about trust "Faith" ! in fact.
Yes maybe it has a bit to do with me growing up as a nipper into Ju jitsu but that is a gentle art and as i taught my mate that trick has nothing to do with hurting anyone but maybe his satanic pride could be humbled and so what if someone is willing to humiliate you why not.
This I can completely understand. I don't know which type of Ju jitsu you did, although I'm assuming it was a traditional Ryu type and not Judo. Either way, there's nothing gentle about it. neck cranks, throws, arm bars, chokes, strangles, leg locks, heal hooks, knee bars and all the various beautiful, yet brutal techniques. That said,,,
Working with several different people from dojo to dojo, and also newcomers, you do get a very good sense of anothers intent. This ranges from a certain look in their eye to body language. In some cases hand shakes. There are people that come to train because they want to be tough, or think they're tough and don't care about uke at all. Their body language tells this first hand. There's been people that just gave me an uneasy feeling. I was right.
Now, In Judo, the kyu grades line up on oneside according to rank and the dan grades line up on the other side also according to rank. At the end of class we all walk by in line and shake hands. The dan grades that are interested in mutual benifit will shake hands firmly and look you in the eye. The others that are there only for themselves, will shake hands like a limp noodle and not even bother to look at you.
BTW, I don't like the word Nipper. Besides, even for a racial slur it's not even correct. Nippon is the proper way to say Japan in Japanese. The everyday way is Nihon. You should know that. Then again, maybe Niher is harder to say?
I think one can tell a lot from ones hand shake and body language maybe it's because i do business with people that i take it seriously i watch their eyes and anything as how that they say things because if i don't trust them i know to steer clear of them as many years of this has taught me the hard way and it's like you know that the person is going to be a problem and cost me.
I find my self to trusting in others and i have to remind myself especially nowadays as the lowlife are out there in droves now.
Shaking hands is definately a cultural thing and seems to mean more here in the US than anywhere else. There's definately a stigma against a weak handshake, and not looking in the eye. Just as it's rude to refuse to shake hands.
I think you can tell a little about someone through a handshake. There's so many subtleties involved. Only those who have the ability to understand body language will pick up on them. But, this isn't something that you can base everything about a person on.