However, framed like this, I do sometimes worry a bit. Atheists who get involved in these debates are often forced into a position of being almost cruel towards religion, and religion being what it is, it starts looking like they are cruel to the adherents of religion, as well as kittens and All That Is Good. I think this is a sad state of affairs, and it is certainly milked for all it is worth by theists who care more about winning "the argument" than about Truth or Fairness.
As novelist and philosopher (I prefer the former designation, really) Alain de Botton puts it, of course God doesn't exist. There's no point in arguing the toss over it. It's a silly idea, end of. We therefore need to move on to how we ought to behave (and no, pedantic theologians, "ought" does not assume a god) towards each other, and leave the arguing behind.
It's tricky though. For many years I tried arguing with atheists (and even myself) that God existed, and that (implausibly) he should be connected with the God of Traditional Christianity, which is a sort of pastiche gleaned from carefully selected biblical proof texts and Ancient Greek notions, retro-fitted clumsily to the remainder of the bible. It was only when I looked more into the bible itself that I was able to recognise it as a purely human creation with no input from any divine source.
And the funny thing is that many people who describe themselves as "Christian", regardless of whether or not they actually go to church or what they profess in their meetings, don't actually believe it is True. They don't believe Jesus is the Son of God or that he was raised from the dead (unsurprisingly to anyone who actually reads the gospels), don't want atheistic arguments, because they don't want to give up what they find nourishing and useful.
So why argue this relatively boring point? Instead I think atheists should concentrate on showing how gods are unnecessary to science, to morality, to civilisation - to anything. To do so in a caring and open way is the best way to get the message across, because in many many cases we are dealing with people who are expressing a humanistic worldview through a Christian (or Muslim or Jewish etc) theistic framework. Let's help, rather than hinder.