This Charles Band produced movie begins with a scared priest (Christopher Lee) showing up at a diner, asking the owner to call the police. But the phone explodes and the owner gets boiling coffee in his face and is electrocuted hen he crashes blindly through a window. The priest leaves--and is confronted by a double.
Then, we go to the main character, a scientist who is getting messages from outer space that predict Earth disasters that will happen. The first is an earthquake in China, then a volcano in Africa. He is eventually drawn to the convent where the priest works and discovers that aliens have assumed the identities of the nuns and priest. Their transport machine malfunctioned because of Earth's instability and they want to get back to their own planet. Before the leader disappears he assumes his true form--a gray big headed alien--and says the planet is doomed and that this is best for the other planets in the galaxy because humans are diseased. In spite of this (?) he invites the scientist and his wife (Sue Lyons) to travel through the door to his world, which they do.
Sort of Charles Band's version of STARSHIP INVASIONS and it has similar ideas to THE DAY TIME ENDED, which was released a year or so later. Recommended if you're in the mood for a weird 70's horror film.