If I found out that there was no God tomorrow, no, I wouldn't go into a murderous rage and begin shooting people. But if I did, and got away with it in this world, I would have nothing to worry about. I could be a veritable Red John and not have to worry about it because only my sense of morality is valid. Everyone else is completely at my disposal, and whether I choose to be benevolent or malicious is wholly my choice.
But if there is a God, then every man is born, to some degree, with the light of Christ. And because of the fall they would know good from evil. How? Not because of Greek or Latin philosophy. Not because of the wisdom of the ancients, but because you're born with it. No one needs to tell you that murdering innocents is evil; that's why no one can excuse themselves at the last day by claiming they were ignorant.
One theologian put it this way:
The ability to have an unsettled conscience is a gift of God to help you succeed in this mortal life. It results principally from the influence of the Light of Christ on your mind and heart. The Light of Christ is that divine power or influence that emanates from God through Jesus Christ. It gives light and life to all things. It prompts all rational individuals throughout the earth to distinguish truth from error, right from wrong. It activates your conscience. Its influence can be weakened through transgression and addiction and restored through proper repentance. The Light of Christ is not a person. It is a power and influence that comes from God and when followed can lead a person to qualify for the guidance and inspiration of the Holy Ghost.
The above reflects my belief. Again, Darwin says survival is hard wired into us to ensure the preservation of the species. But the knowledge of good and evil cannot be hard wired into us except by an outside intelligence.
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