It's not just Muslim practice to marry adults to kids, but other religions as well, including Christianity, especially in medieval times.
Quote:From 380 A.D. to 1971 A.D. the minimum marriageable age was 12 years for females and 14 years for males in the Roman Catholic Church, which was adopted into canon law from Roman law.
Judith of Flanders (aged about 12/13) was married to Æthelwulf, King of Wessex (aged about 61), in October 856.
Beatrice of Vermandois (aged about 10) was married to Robert, Margrave of Neustria (aged about 24; later King of West Francia), in c. 890
Bertha of Swabia (aged about 15) was married to Rudolph II of Burgundy (aged about 42) in 922.
Gisela of Hungary (aged about 11) was married to Stephen I of Hungary (aged about 21) in 996.
Cecile of France (aged 8/9) was married to Tancred, Prince of Galilee (aged 30/31), in late 1106.
And so on
https://en.m.wikipedia.org/wiki/List_of_child_brides
teachings of the Bible are so muddled and self-contradictory that it was possible for Christians to happily burn heretics alive for five long centuries. It was even possible for the most venerated patriarchs of the Church, like St. Augustine and St. Thomas Aquinas, to conclude that heretics should be tortured (Augustine) or killed outright (Aquinas). Martin Luther and John Calvin advocated the wholesale murder of heretics, apostates, Jews, and witches. - Sam Harris, "Letter To A Christian Nation"
