Hey, to each is his own, I am not here to tell a man he can't believe what he wants. If you are to insert your own spirituality and reject O'Sensei's in their dojo, then there is no argument from me. But, if someone doesn't completely replace O'Sensei's philosophy with their own philosophy and instead interprets his writings, with there own meanings and contexts, then they are distorting Aikido. In example, that would be Love. I don't know what O'Sensei was really getting at when he use the word love. But I know it doesn't mean "love thy neighbor as thy self."
To put the Christian context of love, and saying that is what O'Sensei meant by love is bassackwards. He didn't mean it like since logically he wasn't a Christian. Basically, with a little digging on the amateur level a better argument would be for love is it is more akin to social behavior opposed to that of the past history of Japan. Or in terms of psychology, as I don't believe O'Sensei was trained in western psychology.
I have no issue with for example a Christian replacing O'Sensei's philosophy, What I think this is important is people can't go around spouting Doka's or O'Sensei's writing, and putting their own meaning and context behind it, then saying that is what O'Sensei meant. Like something very common and familiar as the word love.
Again on a basic llevel, love could have many different and coded meains when O'Sensei wrote it. I think it is important for people to know that O'Sensei's philosophy isn't something that can easily be understood. That it is so difficult and abstract that even scholars of Aikido have difficulty understanding what O'Sensei meant. Therefore, so does everyone else. And that should be known, right?
I think some deeper research is in order on your part - if you will allow me to say so. When I first said that one would be hard-pressed to demonstrate that there was no Christian influence in Omoto-kyo, and by extension in Osensei thought, I was meaning that it is impossible to suggest this.
You can look this all up for yourself on the Omoto-kyo website - where there are plenty of writings by Onisaburo and plenty of history whereby you could look into other things that show this influence. In particular, you might want to look at Omoto-kyo's notion of salvation and Heaven on Earth, crucifix symbolism, references to the OT creator deity, messianic notions surrounding Onisaburo, Omoto-kyo's participation at the World Parliament of Religions, Omoto-kyo's relationships with Christian groups that were also espousing a universal oneness as a means to peace on Earth, etc.
In the past, I earned several advanced degrees in the study of Japanese religious culture. As I was earning those degrees, I often came across folks that bought into the notion that Japan presented an alternative to Western traditions and ideas - making it an exotic other. However, this "otherness," at least after 1600, was part of the political re-imagination, huge efforts, by the power institutions that have had stakes in Japan's cultural identity. As such, someone studying Japan, and especially things like Japanese religious history/culture, has to be very careful about not buying the party line hook, line, and sinker.
To be blunt: There would be no Omoto-kyo without Christianity, and by extension, there would also be no Osensei without it either. This, I say to the historian.
To the practitioner, again, using your example, who would want to practice or cultivate a love that could not easily include the notion of loving self and neighbor as one and the same?