Mr Jensen's views are informed by his belief that marriage is a "sacred institution" that is "part of God's intimate story".
"If the state does go ahead and potentially change the definition of marriage - or change the terms of that contract - then we can no longer partake in that new definition, unfortunately," Mr Jensen said.
He said if marriage was considered to be only about love, it became "meaningless".
Such a definition would allow for polygamy, he argued.
"Once you say that marriage is detached from children - it's just about love - then, when three people come to the state and say, 'Well, we're all in love', then the state has no grounds, except unjust discrimination, to say why they can't get married," he said.
"When it becomes detached from a child's right to a mother and a father and the sacred institution that it is, then suddenly it becomes meaningless."
Explaining his stance, Mr Jensen said he wanted to spark discussion about the meaning of marriage.
"I can understand why some people might be upset, but our intention isn't to hurt anyone or focus on any individuals." he said.
"Really, our intention is for discussing at a deeper level what marriage actually is."
