Scoff at the urban myth that the Muslims invented the zero.
Sure, mathematician Abu Ja'far Muhammad ibn Musa al-Khwarizmi was hugely influential in spreading the word, but the principles upon which he worked were discovered years before Muhammad. What we call Arabic numerals actually come from pre-Islamic India. Tell your liberal friend that what the Muslims actually invented was not the zero, but in fact zero—except for a few cultural traditions (like harems) that are quite nice for the oppressive male patriarchy.

Psalms 118:8 It is better to trust in the LORD than to put confidence in man.
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Scarlet Chord Ministries   Isa 1:18