Difference between spreading the word and forcing beliefs...
There may be a linguistic or conceptual difference here, but I think when we consider the pragmatic consequences, they ended up being folded together.
Realistically, no one can force you to believe anything. You might just say you believe something, but apart from brainwashing (which isn't really what we're talking about) the only way to get people to form a particular belief is to suggest to these people the beliefs they should have.
The simple fact is that Christianity specifically has a message to evangelize others, and this is going to capture what we mean by forcing your beliefs on others.
Look at evangelizing Christianity and then compare it to some (equally ridiculous) notion like "There are pink elephants constantly watching us."
In the latter case, it's easy to see how we can fault the person for being a bad epistemic agent. They shouldn't believe pink elephants are watching us to begin with, and they sure as heck shouldn't try to get others to believe this nonsense.
The preposterousness of the pink elephant thing is comparable to how preposterous atheists find the notion of a god. Many consider those who believe in god to be poor epistemic agents.
As for me, I think belief in God can be justified - but I think it's like believing that you dreamed you ate a banana split last night. So you believe that - big deal. I don't really care or want to hear about it.
Casually informing others of the teachings of your religion? Perfectly fine if the one you're informing is interested. If not, OH so annoying. But still not forcing.
The above argument is what leads me to think that casually informing others of your religion isn't acceptable. It's just as silly as informing other of what you dreamed last night.
On the contrary, scientists, namely biologists, are constantly finding evidence that creates a plethora of additional gaps in the authenticity of the Bible.
I'd just like to point out, again, that this method of argumentation just won't work. This "God of the gaps" style of thinking limits the power of God to what is unexplained as of yet in science. And what is clear from this as that science and religion must be at odds - which isn't necessarily the case. But if you adopt a "God of the gaps" mentality, every scientific discovery has the potential of slowly eliminating God from the picture entirely.
Any theist is better of adopting the notion of a God who works through nature and natural, physical laws rather than outside them. Otherwise the theist gets backed into a corner, and they tend to get violent when threatened :P