Meditating on the six dhyanas (or "janas") is a kind of single-pointed concentration. One of the side-effects is supposedly "bliss" (sukha). It's strong medicine, and if it works, it will alter your mind - that's what it's for.
I have to say I've never tried it; I was warned off it.
If you're doing it for the bliss, your motivation is wrong, and you are at risk of vanity and playing power-games with people. If that happens, you will suffer harm.
If you were asking why I think religion is not for children, well: I think tales about fairies, angels and Santa Claus are not for children. I don't think you should lie to children, nor encourage them to subscribe to superstitious beliefs. By "children", I mean anyone with underdeveloped critical faculties. I read fairy stories to my kids, at bedtime; but I didn't pretend they were true.
Some religious systems present very interesting ways of looking at the world, the mind, and morality. But it's like hard drugs; it affects your mind and your relationships, and not necessarily for the better. I think that tangling with a religious system should only be done with care, and under appropriate supervision. The matter of how to choose a suitable spiritual mentor is an unsolved problem.
