*affirmative knocks to what everyone else has said*
Caveat: All of the following is my own opinion. Take it with a grain of salt.
The spirit of Aikido is very complimentary with Christianity. Osensei himself said that Aikido was not a religion, but that it would give you a more profound sense of your religiosity, be you Buddhist, Muslim, Christian, etc. I believe Christ taught us to love our enemy, and there's no better way to do that than aikido.
The religious movement Osensei belonged to (Omotokyo) believed that all faiths would eventually be joined into one, like many paths up a mountain. While some of his ideas may conflict with Christianity, practicing aikido would not mean becoming a member of Omotokyo.
One thing I've learned in Aikido, and this is just my experience, is that what you do eventually becomes you. It's very hard for me to distinguish the spiritual from the martial in aikido. Someone else who posts much better than I do once said that the spiritual vs martial argument is like arguing whether a pencil is yellow or straight. The argument is pointless, because it's both and there's no easy way to separate the two.
Aikido will not change you overnight. It takes months and years for that to happen. Try it for a while, and if it doesn't suit your spirituality, you can stop anytime....
Yours in ukemi,