Because believing in alien intelligence is a lot more fun than the fire and brimstone death threats that come with divine intelligence. There is lots of entertainment that goes with alien intelligence and theories. There is no proof of either type of intelligence, so lots of people go with the one that is more interesting and more fun.
2 years ago
Last edited at 1:59PM on 1/23/2012
Hi Orka, There are some pretty good answers above but what you really asked was WHEN.
First, the term "socially acceptable" is meaningless and you may have meant, "When was the idea of alien-intelligence--as-creator popularised?"
In 1968 a German pseudo-scientist named Erich von Daniken (Google him if you must) released a book called "Chariots of the Gods" in which he mooted that reports of angels in the Old Testament were really reports of visiting space ships.
Over a serious of books and TV infotainment programs, he developed the idea and "proved" that many of the discoveries made by archaeologists are evidence of visits by aliens.