We (as a general rule) don't go around bumping each other off because it is unhelpful to the survival of the species.
Survival of self at the expense of the group is short-termism,
Survival of group at the expense of species is suicide.
Religion may codify morality, but religion is certainly not the sole arbiter of morality no matter what the religious types may say.
Your right to believe does not include the right to proselytise regardless of what commandments to the contrary your particular religion holds dear. Some religious people – certainly the 'Religious Right (wrong)' in the US – hold the the belief that Christianity is under a concerted attack because those same Christians feel they are being held back from expressing and propagating their faith.
Tough, you have the right to believe, you do not have the right to demand your faith be enshrined into law or to impose that belief on others.