It's an issue with taxes in general. If a person makes $50K a year and pays $10K in taxes, are they getting a 40K a year subsidy from the government?
No.
But if in the absence of the deduction for mortgage interest they would have paid $12K in taxes, they are in some sense getting a $2K a year subsidy from the government.
Proclamation from the King:
My loyal subjects! Our enemies are growing in power and building up their armies! The kingdom is in dire peril! We must have more roads, so our army can march to the frontiers and hold off all invaders. So from now on all of you must leave your own farms untended for a few days each month and labor to save the nation, building roads. The rules are as follows. All Christians are to build roads for two days each month. All Reform Jews are to build roads for four days each month. All Orthodox Jews are to build roads for six days each month.
Petition from a bunch of Christian subjects:
Your Majesty, why are you giving the Reform Jews a free two day vacation? If in the absence of the deduction for reforming, they would have worked on the roads six days a month, they are in some sense getting a 2 day a month subsidy from the government.
But the whole issue is the what is the quote "right rate" for a tax. Congress could lower the tax rates by 1% for everyone and get rid of the mortgage deduction. So the problem I have is someone saying, I pay 14% in taxes is mooching when you think they should pay 15%.
The issue is that those things that are favored by being allowed as deductions and not being taxed benefit the better off disproportionately.
Paying 14% in taxes when someone with the same income but not eligible for the deduction pays 15% is not necessarily mooching, but the difference does represent a subsidy and it is disingenuous to claim it does not.
When somebody makes a claim that's so completely irrational that the very notion that anyone could possibly sincerely believe it is mind-boggling, (for example, claiming that when you take 14% of somebody's income away from her you're subsidizing her), I often feel the urge to accuse him of being disingenuous. But I try to keep in mind that people sincerely believe all manner of crazy-ass religious drivel for no other reason than that somebody told it to them and they found the drivel sufficiently emotionally appealing that they were never tempted to apply five seconds of critical thought to it. So I generally discipline myself to resist the urge to call him disingenuous, and instead simply explain why he's wrong.
This is an attitude I recommend you adopt toward people who disagree with you. If you accept that we genuinely can't see how a 14% tax is a subsidy even though it's apparently painfully obvious to you that it is one, and you assume the reason we can't see it is because we're irrational victims of some communicable delusion, then, (although you will be utterly and completely wrong about that since the actual reason,
obviously, is that we're right and you're wrong,) you will still be far closer to the truth than you will be if you instead assume, as the authors of the Bible assumed, that everyone who expresses disbelief in your ridiculous doctrines actually deep down believes in your religion and knows you're right and is just being a dick about admitting it.
Paying 14% in taxes when someone with the same income but not eligible for the deduction pays 15% is not only not mooching, but the difference does not represent a subsidy, and it is mind-blowingly absurd religiously motivated reality avoidance to claim it does. What paying 14% in taxes under such conditions actually is is obedience to a tax code that discriminates against the person who has to pay 15%.