A genuine atheist should have no problem at all proving their convictions by committing suicide at a moments notice. Quoting: Anonymous Coward 2898037
A true atheist has no intrinsic value for life by definition.
A true atheist has no belief in a god or gods by definition... that is all.
Also I'll think you'll find that somebody who lacks belief in an afterlife will value their existence far too much to commit suicide to "prove" anything.
There is no better place, no better state of being then to be alive right here, right now, it's all we get so we hold onto it with both hands and we love it and preserve it to the best of our ability.
Life is the ultimate measure of value, because it's all we get.
Religion devalues life all the time, you see it in the actions of Islamic martyrs who blow themselves up in crowds of innocent civilians, you hear it in the language of mourning believers.
"He's gone to a better
"When we die we become perfect.
"We suffer on Earth but are rewarded in Heaven."
"God called him home."
I would argue that religion automatically devalues life by definition as it holds the concept of an afterlife in higher esteem than earthly existence.