If they believe in marriage for religious and/or cultural reasons, then they should most certainly get married. But that shouldn’t have anything whatsoever to do with the government. What’s really appalling is that nearly all churches and other religious groups for which marriage is a religious matter, submit to government’s mandate to require a government license before performing a religious marriage. As one evangelical Christian FReeper insightfully put it, it sends chills up his spine to hear a pastor officiating at a church marriage ceremony saying “By the power vested in me by the State of ________, I hereby pronounce you man and wife.” No religious organization should need a license from the government to perform its religious duties.
What’s the alternative? I agree with you that pastors have a religious authority to perform marriages, but say you have a believer who marries another within your congregation. Then it’s found out later on that the fellow is already married. Part of the reason why they are legally binding marriages is to protect both parties from fraud.
How are you to confirm that he’s already married? If your argument is that only religious marriages are valid, you will get people taking advantage of that provision to get married even though they are already married.
I understand your frustration, up here we have pastors and priests who get leaned on to perform gay marriages, and public outcry and newspaper articles when they say NO!