It is an irrefutable fact: if a person does not fear God, when one of his interests is at stake, he is more likely to violate any moral principle (if any exists) than a person who fears God to avoid personal damage.
To be irrefutable, it must be supported by evidence of the highest quality.
Evidence that I'm not aware of.
So please lay it out for me.
The materialist principle of survival of the fittest is based on achieving the end regardless of the consequences.
The materialist principle that humans have evolved with particular moral tendencies demonstrated by experiment seems to have escaped you. We know that humans are born with a dislike of the one who harms, a liking of fairness and reciprocity, respect for authority, loyalty to the group, and a sense of self-worth through self-denial.
We also know that the rest of our morality, the 'proper' way to interact with people in your family, with friends, and with strangers, with people of the same and the opposite sex, with authority figures such as parents, teachers, doctors, police &c, the observation of milestones such as coming of age, pairing, birth and death, and so on, is largely learnt.
Evidently this is the philosophy that most of the world's wealthy people have adopted, since they do not care about the damage they do to their workers or the planet, if their profits increase.
Yes, there are decent and there are nasty humans in the world. Have you read your bible, and noted that its God demands human sacrifices, massacres of surrendered populations, mass rape, murderous religious intolerance, the subordinate status of women, slavery according to rules (including, famously, how to sell your daughter)? Is that the morality you're urging, or do you have one closer to 21st century human nature as I've mentioned above?
Offended with the obvious truth?
I've set out demonstrable 'truths' above, so that in future you'll be aware of them and able to avoid simple-minded and uninformed statements.