It's not exactly a small change over time. There is ~350 billion in charitable giving in the US per year. If you assume that was taxed at say 20% on average and ignoring inflation or interest * 238 years that's 16.6 trillion or close to the national debt.
Of course our GDP and tax rates has grown over time, but not nearly as quickly as debt interest. So, without doing excessive analysis we would probably have a national surplus if literally nothing else changed in the tax code or spending.
Granted, arguments about lowered GDP and other knock on effects are reasonable. But, suggesting no long term tax breaks seems unlikely.
I understand your position, and I'd actually favor a tax structure that has a much lower rate and almost no deductions (making everyone's taxes far simpler than even the one-page 1040-EZ, and completely automatic). That would leave people more than enough for charitable giving and many other things. But unless that comes as a package deal eliminating all deductions and lowering taxes accordingly, I wouldn't support eliminating a tax deduction for charitable giving while leaving the myriad other deductions.