Why this is a religion? Because it is based in beliefs not in objective, verifiable independent facts.
It is a preconceived idea about reality that had failed multiple times to be validated by observations.
As many other religions their gods are depicted in “human forms”( anthropocentric view ). We already had seen that this view is very narrow and it will always lead to anachronism.
As many other religions it has its folklore of myths and “mystic revelations” that are impossible to validate independently and have to be taken on faith. The list is huge and include from “(in)famous sightings reports” to “smoking gun documents”.
Also as many other religions its members are easy prey of con artists and people that are masters readers of human behavior: the multiple business exploiting this religion is a testimony to that. The many fakes flying saucer footage online are just a try to satisfy a huge demand from that army of believers in their beloved “imagery”. The many “saucer shaped” clouds pictures in UFO related sites is also a testimony of that.
But even more the fact that this is a religion is confirmed by the reaction of its “members”: the nuts and bolts UFO/ET believers, to claims about the reality of the autonomous anomalous flying objects in the atmosphere, anomalies for short, this is a reality that can be confirmed by anyone and the fact that some anomalies respond to direct light signals in daylight or at night had been observed multiple times, but the believers resist to accept that because that reality will cast doubts in the existence of their gods, exactly in the same way that the church reacted to the new scientific views and discoveries that cast doubts in the necessity of a “god”.
The recoil of its members to the idea of direct observations to validate facts is also an indication of that religious character, for devout believers no evidence is necessary then “why bother with unnecessary direct observations?” and “the people doing regular observations are wasting their time and need help”.
But as many other religions facts are irrelevant to them and they will go on in their views in spite of all evidence casting doubts in their beliefs, they are too deeply connected to their Matrix to see anything else, the fact that the topics covered in almost any UFO related site today are almost an exact copy of the topics covered five, ten or more years ago is an strong indication of the stagnation and the religious/cult character of it, as many other religions they are stuck in the past and what defines them or what they study/cherish is always in the past.