Why do you assume the spirituality in Aikido is not your own spirituality ?
I don't think it's disrespectful because I don't think it is really possible to do what you describe. Aikido spirituality is expressed within the techniques. There are choices to be made both in how you move and in your state of mind as you do.
Yes, I think the spirituality and self-defense aspects of aikido are really inseparable, but in my experience no one is going to tell you how or what
to believe in arriving at your decision to as you put it choose to live a more peaceful way of life. Aikido's spirituality/ethics put into practice on the mat are quite compatible with the beliefs/philosophy that mainstream religions hold in common. Most places are going to leave it up to you to draw this out of the practice. Even in Ki-Aikido where we can be rather chatty sometimes, the roots of the talky part of class really have more to do with Dale Carnegie/pragmatic yoga mixed in Japanese culture and nothing to do in any obvious way with native Japanese religions.
I have practiced with Aikido black belts who also happen to be Catholic Priests or Protestant Preachers.
It really depends on you.