I'm not a pure nihilist. Nihilism in general has a negative vibe. I do believe the only purpose in life is whatever purpose you decide to apply to it. However, most of the definitions seem to be very negative, for example -- "a doctrine or belief that conditions in the social organization are so bad as to make destruction desirable for its own sake independent of any constructive program or possibility". Now, while I agree human society has major problems, and believe it is possible we will destroy ourselves, I also believe there is a chance we will get our act together and figure things out well enough to achieve what would widely be considered a successful civilization. I'm not sure how good the chances are...
I believe the creation of religions was inevitable. It was the only way to make sense of so many things. But now we know what causes the sun to rise, how the weather changes, and blah, blah. Which leaves mostly the "why" of everything. Personally I don't think there is an answer to the overall why. Things just are.
Never seen "The Lion in Winter".
“Extinction is the rule. Survival is the exception.” -- Carl Sagan