The charitable deduction creates lots of mischief. Imagine that someone gives $ 1 million to a "charity." Generally, they will then receive a $ 400 thousand reduction in personal income taxes. So, what is actually happening is that the donor is giving $ 600,000, but you the taxpayer are footing the other $ 400,000 without your knowledge or consent.
How much say does the taxpayer have in where this money is going? That's right. None.
Let people who wish to make charitable gifts make them without the taxpayer being on the hook. If they are generous people, then they should be generous with their own money -- not with taxpayer money.
If the argument is that charitable contributions will decline without the financial incentive of a tax deduction, then that alone should tell you that the deduction should be eliminated. Why provide financial incentives, if folks would not otherwise be generous. Maybe these charities don't really merit the support that the charitable deduction provides.
Think of the Clinton Foundation as an example of the problem.
While we are at it, we may as well eliminate the mortgage interest deduction as well, since there is no reason to favor home ownership over renting in the tax code.
Eliminating these deductions could dramatically lower tax rates and increase tax revenues at the same time. A win-win.