Texas Rep. Ron Paul was the only candidate at a Christian forum on Saturday opposed to amending the U.S. Constitution to define marriage as a heterosexual union.

Also appearing at the Thanksgiving Family Forum in Des Moines, Iowa were Newt Gingrich, Rick Santorum, Herman Cain, Rick Perry and Michele Bachmann. Former Massachusetts Governor Mitt Romney was invited but did not attend. Also not in attendance was former Utah Governor Jon Huntsman, who has not placed an emphasis on Iowa.

The candidates gathered around a dinner table festooned with pumpkins as moderator Frank Luntz kept the conversation flowing for two hours as nearly 3,000 religious and socially conservative activists listened in.

Paul, who has previously said he's personally opposed to gay people marrying, said that the role of government is to preserve liberty, not mold people or society.

“Our values should come from our family and from our church. But once we say, 'Well the liberals are doing this because they want this economic interference and we're going to have perfect balance and fairness.' They over do it. But you can do it on both sides. You can say, 'Well we're going to make people better by having more laws.'”

“The law can't reflect the morality of the people. If you do that, you have embarked on something where you sacrifice liberty,” he added.

(Related: Rick Santorum: Gay marriage will doom America.)