Mormons only started in the 1800s.
Need I say more?
Being around longer certainly doesn't make you more correct.
A lot of gods predate Yahweh.
This isn't some sort of trick.
I want a Christian's opinion on why the Mormons are wrong.
We know the origins of Mormanism are highly questionable.
But, so are Christianity's.
So, preferably without using the "my book is right, your book is wrong" argument (objectively they cancel each other out)
Let them have it. If you would be so kind.