Have you ever meditated? Yes? Just continue to read. No? Ask somebody who does, better ask people with different faith and then read this.
I meditate and this is my experience. It generally starts with a good thought or an image. In my religion (Hinduism), it's recommended to think of some phrase (like Om or Bramha or Om Namah Shivay). I am sure similar for other religions too. So we start our meditation being religious. Have you noticed what happens after 5 minutes? Or 10 minutes or 15 minutes or an hour for some of you? You forget the phrase. You forget the image. The thought disappears and what you find in place? Blank! Silence! Space! That's the second level of meditation and this experience doesn't discriminate people. Everybody can have any experience independent of their faith. Doesn't this prove we are ONE?
Not sure? Try meditating if you haven't done for a while or learn if you don't know how to. No need to take a course or buy a book-just ask somebody who does. Experience the ONEness and share with others.