Tools, science, philosophy. Those that are not harmful, anyway. Well, anything can be harmful when misused. Therein lies a problem.
One thing I have a very hard time enjoying in any way, shape, or form is religion. Religion is too harmful; it could be interesting if it weren't taken too seriously.
Yet I remind myself, as with anything, it is only a tool in the hands of a person. The way that person uses it determines whether it causes harm or not.
It's just that I almost never run across a person wielding religion who doesn't remind me of a drunk teenage boy with an AK-47 and a 6-foot high stack of 7.62X39 in little 20-round boxes, a pile of loaded magazines; sitting there looking at an abandoned field filled with unbroken glass jars, a couple of boxes of old, sweaty dynamite, and a rusted out car, and a couple of crows.
And I'm usually a crow.
Still, I would never dream of using the force of The State to tell someone what they can believe, or preach. As long as they don't use those beliefs to create "laws" it is none of my business- beyond excusing myself from their presence when they start. And I would never try to use The State against them even when they don't return the respect. In that case, however, I will not hold my tongue.