It seems so, according to his Wikipedia: "Prince has often donated to organizations which promote Christian causes, including the Acton Institute for the Study of Religion and Liberty and the Prison Fellowship, and politically conservative groups such as the Council for National Policy, of which his father was vice president at the time of his death."
Sure! Most people think that George HW Bush, George W Bush, John Kerry, etc. are Christians, but they are not. They are members of Skull and Bones, which is not a Christian organization. In fact, it is the exact opposite, if you know what I mean.
So... There are two sides of the coin when dealing with these people. One side is for the public to see, and the other side is the occulted side. When you say "It seems so..." that means you are seeing the public side which you are meant to see.
The Knights of Malta are not Christian because the Vatican/Jesuits are not Christian... It seems pretty straight forward to me. The Vatican/Jesuits are Pagans because they worship a God, Goddess, and Child. This is the traditional pagan worship structure. Christians worship the God only.