I second ender's response.
Science doesn't need to prove or disprove anything at all. Doesn't need to prove whether romantic love is anything more than hormones and electrical impulses with the general purpose of motivating reproduction so that monkey men may continue for as long as they are able. Similarly need it prove that love of children exists is a evolutionary development to motivate us to care for them until they too procreate. Whether one wants to accept that's all love is because that's all that science can tell you is another matter.
Whether one "believes" or "knows" love to be more than that (or not) is obviously up to each person, but I can't imagine holding such a stilted view of life. Maybe if I had no concept of love beyond what the scientific method can tell me I'd also put that particular concept on the plane of mermaids and unicorns. Not to say atheists take such a stilted view of love, but belief in God is similar in terms of "knowing" without scientific proof.
I can also speak for myself, but believing through faith doesn't work well for me. On a few occasions I have asked Warbler or ender about how they can believe a certain thing on faith alone. I ultimately don't fully agree but I respect that they have it.
Granted there is a kernel of faith - in the same way that I have faith that love is more than a manifestation of biological dictates (though they no doubt play a big role). And if the goal is to convince somebody of existence of something, I agree the burden of proof is on the person making the claim. Plenty of philosophers have made arguments based on reason for God's existence but it's a practically futile effort if somebody requires scientific proof.
I respect the view that you can't disprove God and don't believe since you haven't seen evidence. It's those who claim that they know that there is no God. Leonardo takes his own route in getting to that point. And perhaps it's that variety that inspires your objection to generalization. However, atheists generalize about theists in this debate with the overarching objection that theists 'can't prove.' Well I'm saying atheists can't disprove and thus while they may not believe, they do not "know" that there is no God. Whatever unique reasoning underlies the claim doesn't change that.
Unless one has searched everywhere, looked to the source of the information, or shown evidence that something is excluded from existing (eg I'm the only person inhabiting the space I'm in), one cannot say something does not exist. Even with unicorns and mermaids, it can be ignorant to say one knows that they do not exist. That may sound silly, but if we are speaking about knowledge in any concrete and consistent way, we can't say that we know that don't exist simply because we don't have evidence.
I see nothing in science that makes the existence of a deity improbable.
Leo feels he knows God does not exist. Many religious people are at least as certain that God does exist.
Why should either of these concern us to the point of discussing it with nearly as many words as we already have?
I want to emphasize how much I agree with ender. I like you, Leo, Bingo, Frink, et al. since it can be hard to discuss such topics without coming across as strident. I find it an interesting discussion but it unfortunately comes down to somebody being less than a good guy. Like I told Warbs, I try not to discuss religion. At least one side sees no valid argument to even have and people only end up being disgruntled.