Not even close.
Only one of the 56 was an active clergyman, and that was John Witherspoon. Witherspoon was a Presbyterian minister and president of the College of New Jersey (now Princeton University).
A few more of the signers were former clergymen, though it's a little unclear just how many. The conservative Heritage Foundation said two other signers were former clergymen. The religion web site Adherents.com said four signers of the declaration were current or former full-time preachers. But everyone agrees only Witherspoon was an active minister when he signed the Declaration of Independence.
One issue that may contribute to the confusion about which signers had a history in the clergy is that during the time the Declaration was written, people who studied at universities often received doctorates of divinity, a common degree designation, even if they were not working clergy, said Mary Jenkins of the Independence National Historical Park. As for religious affiliations, all of the signers were Protestant Christians with one exception, Charles Carroll of Maryland, who was Roman Catholic.
We'd like to give Huckabee every benefit of the doubt, but even if you consider former clergymen among the signers the best you could come up with is four. Out of 56. That's not "most," that's Pants-on-Fire wrong.