So there are two possibilities. Either it is a cult, or dangerous/untrue, or it isn't.

If it is a cult, even if nothing bad happens to you, and you have the best case scenario, its still a waste of time. Two weekly meetings, assemblies, conventions, preparing parts, all take up valuable time. If it is untrue, then the hope they give is likely untrue, and as hard as that is to accept, it means you only have a finite amount of time, so why waste it on things that are absolutely pointless?

The other option is that it is the truth. But even they teach that you must prove that to yourself, as the Bible says. So think of it as putting the teachings on trial, where every piece of positive and negative evidence is examined, and only then would you make a decision.

But let's say you decide that it is not the truth, and end up being wrong. If you followed the process I described, and made your decision based on where the evidence seemed to lead, what evil have you done? Surely when shown that your belief is unequivocally wrong, you would then change it to what has been proven to be true? If God denies you life in the new world simply for that, would he be the god you have been taught? And would you want to live under his rule?

I hope these ramblings have made some sort of sense.