I don't go into the spiritual side of Morhei Ueshiba. If I do meander that way, I do so as little as possible. It is a very complex area. Instead, I focus on the point that Morihei Ueshiba made -- you didn't have to follow his exact footsteps. He said aiki made everything better and somewhere he told one of his students that aiki would make religion better.
So, of the two things that are primary influences in Morihei Ueshiba, martial aiki and spiritual ideology, the former is a must have and can be trained while the latter can be any outside spiritual influence that is similar in ideology.
So, yet again, we find that Modern Aikido is very different than Morihei Ueshiba's aikido. Modern Aikido created a complete package of martial and spiritual while Ueshiba's aikido used Daito ryu aiki merged with Oomoto kyo ideology. Ueshiba himself said he was a man of budo and not religion. I believe it was Kisshomaru who said that his father got angry when people called him religious.
As for the spirituality side, it didn't *seem* to matter to Ueshiba if you were Buddhist, Catholic, Protestant, Wiccan, etc. With Ueshiba, it was an *outside* spiritual influence. With Modern Aikido, it is one complete package. (AGAIN for the masses -- NOT stating either are bad just that they are different.)
Why do I not go into the spiritual side in these posts? Because it is an open field, dependent upon each individual person to fulfill as, I believe, Morihei Ueshiba envisioned it. What most people are doing in trying to be a better person, spiritually, would fit with this ideology. Why try to include nearly every religion, every spiritual ideology into aiki? As long as you are similar in the peace, love, harmony, make the world a better place, you're good to go. On the other hand, aiki is a specific martial quality. So, most everyone is fulfilling the spiritual side of Ueshiba's aikido. Why debate that? It's pretty much a given. You study Modern Aikido, you're fulfilling Ueshiba's spiritual ideology. You might not be studying the *exact* spiritual ideology of Ueshiba, but it doesn't matter. Ueshiba said it was okay to pursue your own way.
The martial aiki from Daito ryu would make it better. Now *that* idea is a whole different thread and a subject just waiting to be explored. How can aiki make religion better?