Christian polemicists read Islamic practices as derivatives of Judaism and Christianity

Evidence

Circumcision and the prohibition of eating pig’s flesh are the most important examples. Circumcision was occasionally represented as a false baptism, like the ablution; confirmation might have been a happier, though not a more useful, comparison, and it came to be more usual in the seventeenth-century period. Both of these aspects of Islamic Law were usually treated as examples of the derivative character of Islam, as compounded of Jewish as well as Christian elements. — Norman Daniel, Islam and the West, 1267

Categorization

• XREF: connects to: Protestant-Catholic-Islamic parallels in polemic relied on incredibly thin points