I'm quite familiar with the arguments: tithing is required for a Temple Recommend and to enter the Celestial Kingdom; the LDS Church doesn't disclose even semi-detailed public financials or to those who pay tithes; the LDS Church has massive income-producing holdings in cattle ranches, malls, radio stations, and the like; the LDS Church does very little humanitarian work other than for LDS members, and that's done primarily from fast offerings and other offerings and not from tithes; and so on.
But I'm not the person paying the tithe, Mitt is. If he and other LDS members want to tithe, or tithe because they've been taught that they must tithe to be exalted, enter the Celestial Kingdom, and be Families Forever, then that's essentially LDS business.
As for the comment: "I guess Mormons understand the principal: “givers gain”." That may be true, but they also realize that they can't attend their children's weddings in the Temple, or watch their grandchildren's baptisms in the Temple, or be married for eternity to their sealed spouses, without staying current on their tithing. And if they fall behind, they have to make it up in future years. Exaltation's a gain, and a lot to gain. But it's your choice.
As for the statement: "The correct LDS phrase is "10% of your increase".
First, the First Presidency has determined that means 10% of your gross. Second, there were two revelations on tithing. Doctrine & Covenants 120, which sets up the Council on the Disposition of Tithing is the one that's always cited.
However, Tithing for Mormons (and I say "Mormons," because the revelation came before the current LDS church was established - this was before the leadership crisis, and the hyphen in Latter-Day Saints), came from D&C 119, and had two parts, in pertinent part:
“I require all their surplus property to be put into the hands of the bishop…and this shall be the beginning of the tithing of my people.” (D&C 119: 1, 3)“And this shall be the beginning of the tithing of my people. And after that, those who have thus been tithed shall pay one-tenth of all their interest annually; and this shall be a standing law unto them forever…” (D&C 119: 4)
“Verily I say unto you, it shall come to pass that all those who gather unto the land of Zion shall be tithed of their surplus properties, and shall observe this law, or they shall not be found worthy to abide among you.” (D&C 119: 5)
So with the initial revelation, Mormons paid their surplus to the bishop. And only those who paid a surplus paid 10% of their interest. The communal nature of paying your surplus was a common thread in early Mormon thought - the United Order involved common property.
As for the comment: "One of the questions you answer at your temple recommend interview is, "Do you pay a full and honest tithe?"."
I don't believe that's the current wording. I believe the current question is: "Are you a full-tithe payer?
These thoughts offered for historical perspective and to clear up what I believe may be some mistakes. Again, my view is that it's Mitt's money, Mitt's church, and LDS teachings. I support the right of Mitt, FR members, and others to their religious beliefs, although they may differ from mine. When I butt heads with "LDS", it's over the issue of faithful history versus academic history, not over whether LDS members should have a right to believe and practice their beliefs.
Jeff, is the current TR question: "Do you pay a full and honest tithe?" or "Are you a full-tithe payer?"
If the former, when did the question change?
watch their grandchildren's baptisms in the Temple
Baptism happens at the local church building, not the temple, and the public is welcome. It is "baptism for the dead" that happens in the temples, and is not something that people tend to "watch."