The abrahamic religions all worship the exact same father god of Abraham who was the Canaanite "god of war". This god was said to be exceptionally jealous and warred against anyone who worshiped any other deity but himself. This has spilled into their three main factions. The abrahamic jews, christians and muslims all claim that they alone are worthy of salvation and eternal life, and all war against each other (and everyone else) out of petty jealous claims that only "their" version of the same thing believed differently is the correct version. There are even jealous rages within their own factions. Infighting amongst hasidic vs orthodox jews, baptist vs protestant vs whatever christian, shiite vs sunni muslim. It's all the same thing, but "interpreted" differently.