I like to compare religions to languages. They are tools to speak about the unspeakable, but they don't necessary oppose each other when they have different doctrines, like French doesn't oppose English when it calls “maison” what English calls “house”.

By definition, God is a reality that exists outside time and space, there's no way our mind can define it. But like you need a language to speak, you need to practice a religion to develop your spirituality, even if you know that your religion is not the only way to develop it. You can also speak more than one language, and you can practice more than one religion, but it's harder.