Here's the difference: The priest does not decide what rules you must follow, and he does not send you to hell, nor does he propose to. In a stateless society, a natural law, private-property-based common law would emerge in a decentralized manner. Private arbitrators, voluntarily hired for the purpose of decision-making on a case-by-case basis, would use their knowledge of precedent and legal theory to make wise and informed decisions. The customers can choose to abide by the decision or not. This is the difference between law in a state of anarchy and law under a monopolist State. Similarly, in a church structure, the priest is merely imparting his knowledge of God's law to his fellow man. They are free to believe him or not, and to act on his advice or not. The priest does not follow you to your house, point a gun to your head, and make you say Grace before every meal.

But again, I have to point out: If you don't believe the claims of Christianity are true, then in your opinion there is no God to pass judgement on you. If that's the case, then what's the problem? All you have is some people over here who believe something (falsely, in your opinion), and they're not forcing you to do anything. The only reason you might have a problem with it would be because you believe that it IS true, and you don't agree with the situation you're in. The reason I liken it to the forces of gravity is because if God exists, and He created everything, then the laws he put in place, both natural (like gravity) or moral (don't steal, don't kill) must be taken as facts of the reality that He created, and we must grapple with the facts of nature and consequence in this world. The moral law is simply the path to God. If you don't wish to choose that, then you're free to do so. You'll get exactly what you chose. Hell is not a punishment in the sense that most people think. It's the absence of God. You're free to choose it. You just might not like it, though. But if you want to move toward something good in the afterlife, then there are steps to take and steps to avoid. I am free to smoke, drink, and eat junk food. But if I get fat and cancerous and diabetic, it would be ridiculous to say "You mean if I want to be healthy, I can't do these things? That wasn't much of a choice. That's not freedom."

Once more, to be perfectly clear, it is not the religion itself that is doing something to you, or restricting you. It is your belief about the nature of existence that restricts your actions. And if you don't believe God exists, why would you feel restricted in this way? And why would others' belief in the existence of a God you don't believe in restrict your freedom in any way?