I was raised in a strong christian household, as well. My father is a missionary, scholar and a very spiritual man. What that has to do with anything is probably less than nothing (other than my education of christianity). When you ask about religion, it seems like what you really want to ask about is christianity. Am I wrong?
Right or wrong, I think religion and martial art have little to do with each other (or should) other than how far you
will go in your
conflict resolution (ie: will you kill someone, will I skip church for Aikido practice, Is bowing to a picture of O'sensei Idolatry, etc.).
Gaijin (non-Japanese) tend to romanticize the "Ki" in Aikido with spiritual/religious attributes but that isn't correct in this case.
Let's look at the meaning of "Aikido":
"Ai" can mean: Love, balance, harmony, homeostasis, proper fitting, and much more.
"Ki" can mean: Spirit, kinetic energy, force, blood flow, the gas that heats your home and much more, also.
"Do" means basically the way or an enlightened path (...another topic, for sure!
The way of proper fitting with/to kinetic energy forces.
If someone holds there hand close to your face, you can feel the heat ..that is "Ki". I can feel the "Ki" when my wife comes home from work. You can also feel this "Ki" when someone stares at you with "daggers" from across the room. This is an example of bad or negative "Ki". Is negative Ki spiritual? (Dogs can sense fear, ..fear is also a negative "Ki)
Our bodies run on "Ki." Our brain activates/"fires" our muscles with chemo-electrical impulses that generate a measurable magnetic force field. Our breathing cycles are the "engine" that replenishes the body with oxygen and fuels our cells. Our heart is part of this engine that pumps the fuel to... blah, blah, blah. This is a scientific fact. It happens whether you believe in a God/religion or not.
Developing sensitivity to this energy is a very entailed process or path. Aikido techniques can be
the understanding of how this works, to some degree. This is a "dance", if you will, of the timing, movement, and rhythm of Aikido. When you understand how the body works and the relationship of intent, connection, and energy, it works much better. I want the "Much Better."
I won't get too deep into this, but knowing how to cause reactions in the muscles of uke and how to use the stored energy in those muscles to "fire" a recovery motion is using "Ki". It is essential to understanding Aikido. If that conflicts with your religious beliefs, I think you should be true to yourself and do aerobics. Without "Ki", Aikido is just ...."Aido"? (