Would the eurpeans have take the same course in africa if the people there had been christian like them selves

Well, that's an interesting question: we don't know for sure.

So, on the one hand, they claimed that they would not enslave other Christians, and we have reasons to think that they would treat other Christians as "equal" (that was the difference in Europe between the Lithuanians, which converted to Christianity and still exist today and Prussians that didn't and don't), which would mean that they would not.

But on the other hand, what they did was already against Christian morals, and i don't find it unlikely that they would have found an excuse or a loophole; in the end, slavery was directed by greed.