Liberals don't care about moral principle. Libertarians think people should be trusted to police their own behavior. To the latter, government should intervene only when your conduct might harm others. A free society should allow individuals the freedom to be stupid and to offend - as long as what they do doesn't harm others.
"Show me just what Mohammed brought that was new, and there you will find things only evil and inhuman, such as his command to spread by the sword the faith he preached." - Manuel II Palelologus