Morality: Is it Logical?

A friend of a friend asked me: “Doesn’t it make a lot more sense to derive your morality from logic and reasoning than from a morality that is dictated to you by religion?”

I answered him with this:

If we are nothing more than animated meat responding to stimuli then, yes, it does make more sense to derive our morality from logic and reasoning. However, naked logic and calculated reasoning leads me to conclude that being honest, cooperative, and self sacrificing is a sucker’s game if it doesn’t benefit me directly. It’s a fool’s errand.

Here’s a logical morality for you:

There are, indeed, logical reasons to be honest, to cooperate, and to be self sacrificial when it benefits me. However, there are no logical reasons for me to be honest, cooperative, and self sacrificial when it doesn’t benefit me. There are also very logical reasons for me to be deceptive, manipulative, and selfish if/when it benefits me. This is a perfectly logical morality.

As Christians, we believe that humans are morally aware because we are “made in God’s image” and we have an internal “moral compass” because God made us so. We believe that honesty, selflessness, and cooperation (among other things) are “morally right” (in most cases) regardless. But take God and His laws of love out of the picture for just a second. In a purely naturalistic/materialistic universe is there any logical reason for an individual to be honest, self sacrificial, and cooperative even when it doesn’t benefit them? What do you think?