So what should an Atheist - more than just a nihilist - do when the terrorist has a gun to his head? This one would tell them to pull the trigger.

If you really like chocolate, and someone comes and points a gun to your head, forcing you to claim that you dislike chocolate... Would you ask them to pull the trigger? Yeah, you wouldn't, and while that happened, you made a statement that you sincerely regard false. That much about the Truth.

Few moments are usually not worth rest of your life. The choice of giving your life for something shouldn't come just because the alternative is mildly inconvenient.

I do agree however that we underestimate how minor-looking things can actually be of a huge importance. But, atheism doesn't really seem to belong to that category.