:-)
A is representative of the tribal deity known as the god of Abraham.
Group X is en toto all those who followed that tribal deity prior to the time of Christ's corporeal ministry, and also those who follow the same tribal deity now and don't believe in the divinity of Jesus Christ.
Group Y then, previously unmentioned if explicitly implied, is en toto everyone who believes in the divinity of Jesus Christ and don't believe in the tribal deity known as the god of Abraham.