How do I respond to an unbeliever who asks, "Who created your Lord?"

One should not debate people of desires (innovators) except for those firmly rooted in knowledge. The question "Who created Allah?" is rationally impossible. Allah is the Creator of all things, and it is inconceivable that He could be created. This question is from the whispers of Satan, so when it arises, one must seek refuge in Allah and stop. For if the Creator were in need of a creator, He would be among the created, and this leads to an infinite regress, which is rationally invalid.