But that money donated IS NOT taxed (as per your Gene Wilder meme indicated.)
That premise is false.
People donate money to charities to (among other altruistic reasons) AVOID paying taxes on it. Plain and simple. Sometimes it CAN be a huge difference. Here, lemme learn ya something:
Say you make $157,500. That's your TAXABLE income. You will pay $50,400 of that in federal taxes (32%)
You keep: $107,100
Now say you DONATE $1000 to a church. Your TAXABLE income is now $156,500 (24% bracket) so you pay $37,560 in federal taxes.
You keep: $118,940
So for donating $1000 you KEEP $11,840 you would have paid in taxes.