"Any set of arrangements can be put in place. Once you change the boundary, where do you with any sort of logic draw that boundary again?" he said.
"This is a pathway which will lead to anybody claiming whatever agenda they like, just two people, being able to legally by married in a relationship."
He likened same-sex relationships to simply friendships.
"I have an affectionate relationship with my cycling mates, we go cycling on the weekend, but that's not marriage," he said.
"The law has a place historically, culturally, across civilisations because it's there for the protection of the vulnerable".
The "vulnerable" people could include children or one half of the married couple, he suggested, while same couple wishing to be married were in it for the "gratification of individuals".
When pressed on fellow Liberal MP Tim Wilson's commitment to his same-sex partner, Andrews again likened the relationship to a "friendly" one
"That's fine. I have commitments to friends; I have affectionate relationships with friends as well.
"I hope he's his (Wilson's) friend as well as his partner, if you know what I am saying".
Andrews comments comparing cyclists and same-sex couples has riled some on social media and just left others in fits of laughter.
