Was the fire that destroyed much of Notre Dame Cathedral just before Easter set deliberately, and if so, by whom and for what reason?

Unfortunately, this was, as you saw intuitively, an extraterrestrial design and implementation via the Mercenary Army Program. So they conceived of this tragic happening and employed their minions, the humans in the Mercenary Army Program, to carry out an attack on this edifice using a cloaked craft and an energy beam weapon to ignite combustible material within the building, and that was child’s play for them to do so undetected, even though workers were present. There may well be a benign explanation offered, but it will be a cover story carefully manipulated to come forth—this is often done as a way to cover their tracks, so to speak. They simply could not help themselves, in advance of Easter weekend, to darken the lives of many worshipers who would be thronging to that great cathedral for services and take great delight in the experiencing.