Why Satanism?

[Cassiopia]

Granted I don't know much at all about this LHP. But it strikes me as odd that someone who rejects the authenticity of the Bible would acknowledge any aspect of it as truth.

So what made you decide that the Bible is based on reality at all, or enough to accept that the Satan character is actually real? And actually is God? Did you ever consider that maybe the whole Bible is fiction and that neither the God of the Bible or Satan exist?

I came to Satanism as an extension of my pagan beliefs and practices. I do not believe in the bible at all and my ideas about Satan go back to ideas of many traditions that pre-date Christianity.
Personally I believe in an actual entity, but I think that entity can be experienced and understood in many ways;- and has been interpreted differently by various traditions over time. I also think Satan represents our own selves and our own potential.

My next question is, why do Satanists or LHPs in general take to 'dark' symbolism? For example, DofP above has a skull image as avatar and Jason you have 'Destruction and lols' in your Religion title. Is darkness and death an actual major feature of these religions/philosophies or do followers just happen to have a fascination for that side of life?

I like dark aesthetics, just because I do. I am not sure if that really has much to do with my following a LHP.
I am not particularly into skulls, blood and death although I use some of those images in certain rituals. Mostly I find there is something quite beautiful in things that are sometimes described as dark.
For me it is all about balance. The LHP is about acknowledging all the darker aspects of ourselves and working with them rather than pretending they are not there. I guess I take a rather Jungian view.

But aren't most LHPs responses to the original religions? Meaning that they act to emphasise what the original ignores?

I don't think it is correct to say they are responses to their original religions. They are simply aspects of those religions. For example in a Tantric context, "left-hand path" and "right-hand path" refer to differences in ritual practice, not in belief. Tantric "LHPers" believe many of the same things that Tantric "RHPers" believe: that there is an Absolute, that we should try to integrate ourselves with it, and that our selfish passions and fears are major obstacles to enlightenment. But while RHPers attempt to conquer their dark sides by conforming to socially conventional religious practices, LHPers attempt to exhaust their dark sides by immersing themselves in whatever they personally find to be tempting, disgusting, or downright terrifying. The object is to remain spiritually pure even in the midst of great distraction or corruption; or to put it another way, it's about finding the road to heaven by putting oneself through hell first.

As a Satanist, my own view of the path is not quite the same as the tantric one, but from whatever perspective or tradition you come from the Left Hand Path is always supposed to be a route to spiritual growth.