The central belief that all of Christianity hinges on, that of the resurrection from death of Jesus of Nazareth, is a slippery slope, at least. If one chooses to believe that miracle happened, it isn’t too far a stretch to believe in the feeding of the five thousand, or in the healing of the sight of the blind man, or the other miracles that Jesus was supposed to have performed in the Gospels. If you can believe in the resurrection, everything else is on the table.
And there is no shortage of miracles in the Old Testament either. The production of the stone tablets on the mountain after witnessing a burning bush that is not consumed by the fire, the plagues of Egypt before Pharaoh sets free the Israelites, the parting of the sea for the Israelites as they flee Egypt, the production of mammon in the desert to feed the Israelites, and so many more.
So if one believes in all the wonders of the Old Testament, is it such a stretch to believe in the resurrection? Not really. Or if one believes in the resurrection, why not believe in all the miracles of the Old Testament? It is a leap of faith on both counts, no matter how you look at it.
Can one be a Christian without believing in miracles? Well, if you don’t believe in the resurrection, it’s hard to claim that label. But if you do believe in the resurrection, you have no case against the miracles in the rest of the Bible. One can believe in Jesus’ moral teachings, and so be a follower of Jesus in a way, but some of the things Jesus is quoted saying, and the wonders he is recorded as performing, would have to be overlooked.