Because
1)What Jesus actually said was ‘He wouldn’t appoint anybody to dispense spiritual food’ (Mathew 7:21-23); and what is purportedly said by Jesus in Mathew 24:45 could not have been uttered by Jesus because of the very wording “slave” used in tacit endorsement of the prima facie inhuman practice of slavery, about which Abraham Lincoln said “If slavery is not wrong, then nothing is wrong.”
2)People know what is wrong and even hate it when it is found in others.
3)People know what is right. See how the world responded with prayers and unsolicited help when twelve boys belonging to the Wild Boars soccer team and their coach were caught up in a cave in Thailand.
4)People know even what becomes wrong which was once treated as right. When Trump family started charity it was praised as good, but that very act is now seen wrong because “New York state attorney general alleges charity illegally coordinated with Trump campaign.” (https://www.wsj.com/articles/new-york-attorney-general-sues-trump-foundation-alleging-illegal-coordination-with-trump-campaign-1528988443)
5)Claiming "our God is true and your God is false" is the greatest joke just like each country calls ocean as theirs even naming it as Indian ocean, Arabian sea, Caspian Sea, Adriatic Sea, Mediterranean sea …etc, yet we all know there is only one ocean.