Why we do what we do

"woke up this mornin'
and-a all that love had gone
your papa never told you
about right and wrong"

One of the recurring themes in debates between atheists and theists is the seemingly unjustified (from the atheist point of view) nature of many of the restrictions/actions which believers are obliged to by their religion. Some examples include abstention from pork, alcohol or praying.
I recently had one such debate where the point was raised followed by this remark from my religious counterpart:

The fundamental reason that a person follows any of the Torah is his/her will is to have a relationship with God. That's the value. Relationship is based on doing His commandment. Therefore, by not eating pork I achieves this goal by definition

The context to this remark was a discussion of the way values(moral and others) are derived and justified.
An atheist has a hard time coping with such a statement (the discussion almost reaches a state of paralysis at that point). This post is an atheist perspective on that statement.
At first it would seem like a dead end:
Theists believe in God. God said this and that. Conclusion: this and that is true and we must do as God said.
An atheist thinks: Pfff!... this is silly! God does not exist, therefore this and that is rubbish and there is no reason on earth for doing it!

As an atheist, I think that in a way religious people are given a "hard time" on this issue for no good reason (but in another way I think there is a very good reason, which I'll leave to another post). This is not because I think that perhaps there is a slight chance that God does exist, so maybe what they are doing might make sense. What I mean is that we are all religious in our beliefs and actions, even without believing in God.
It is a consequence of people's innate tendency to follow. As children we tend to follow what our parents tell us, imitating their behavior. Growing up we are all the time surrounded by authority figures which tell us what is right and what is wrong. As grown ups we adopt the codes of conduct of the society we live in, and in our working place we assume the role we are given without asking much questions.
It is built into us.
Hard wired into our brains.
That is the way evolution designed us. Obedient creatures are better adapted to living in a society. Social creatures are better survivors. That is why there are codes of conduct in any social living being.
Well, you might say, so what?! humanity has reached a stage where we can transcend those primeval urges. Science and rationality are now the driving forces of the modern man. And I say - nay. I think there are many situations in life in which most of us are blind followers, as rational as we would like to think we are. Our first instinct is to merge in and assume the position given to us, and only then, maybe, to rationalize about it. This is most evident in political discussions, where any laymen has an opinion, but when confronted with the opposite stance will find it hard justifying his views.

It is impossible to act completely rational all of the time. This realization should be emphasized more in atheist-theist discussions, as it is a step towards bridging the seemingly uncrossable gorge between the sides, and is an interesting point to analyze on it's own.