I remember hearing complaints over newer study books versus "You Can Live Forever on Paradise Earth". The complaint was that the WBTS scaled down newer books by only teaching Witnesses beliefs and removed portions that disproved other religions. The WBTS did.does an excellent job convincing its people that there can only be one true religion, one true god, and they are it.
So, once you come to learn the Truth about the Truth, it is easy to come to the conclusion that no religion is correct and there is no god.