I believe in both
It's a floor wax and a dessert topping.
I do not see any evidences for god(s), whatsoever. Nor do I see that "we would all be like orcs" as a result of evolution alone. Society doesn't last long if you murder each other, bear false witness against one another, etc. Sympathy, Empathy, Trust, Love - Those emotions, and behaviors come from necessity of living together in groups - and indeed we see them even in simplified form among many animal societies as well. We've just taken them further.
Whether belief in a god is a necessary thing is another matter - certainly mythology, faith and organized religions have played important roles over the millenia. We seem hard wired to want to believe - and perfectly content to create gods to fill those gaps if needed. The actual existence of god(s), is not as important as the role the people who believe in them play.
Because you don't want them coming back and stealing your cow, esp as you hated it when someone stole your "special" sheep
This is the second time today you've mentioned "special" sheep. Did you experience a loss recently?
Evolution/natural selection or God are not the only possible explanations of human behavior. Psychological development and socialization are very complex processes and can lead to a number of behaviors be they rational, irrational, good or bad. The guilt associated with stealing or other acts is instilled by the society one is raised in, through education or the threat of punishment, because that feeling helps control behavior and thus protect the society as a whole.
"Psychological development and socialization are very complex..."
First you have to get to the point where those processes can occur. Phycological development may occur in a, somewhat, less mentally developed species but socialization requires some complexity and more advanced mental development. The question on that regard is how complex or advanced must be the mentality of the species for the socialization process.