If a corporation, or a union entity makes a donation or a contribution, it prevents the share holder, or the union member from deciding how they should dispose of their income.
Now usually a corporation and a union are not seen in the same light, but this is a great case for abolishing charitable contributions by both. You see that money is usually directed toward political causes, often not in step with those who should have actually made their own decision. The money "donated" is actually profit due the shareholder, or dues paid that should have gone to benefit the enrollee. The larger overseeing body, (corporation or union) took it upon themselves to make that decision for the actual owners of that income. In a free society, shouldn't that option be granted to those who actually own the funds?
Now the first objection to abolishing the deduction of the corporate and union tax is that it would hurt the charities. Now what I'm thinking is if the charitable donation deduction is still intact for individuals, the income passed down to the shareholders in the form of dividends, or the lower union fees will be directed as charitable contributions by the individual, which is what this country is all about anyway. We work on the principle of individual liberty, and allowing a larger entity make decisions for us, robs us of the ability to make our own choices, or strips us of some of our liberty. Because liberty is the ability to make choices. Don't you feel best when you've made the decision of how your money is spent?