In ancient times, once a group of highly intelligent scientists (aliens) from outside the world, genetically modified the cells of some primitive people of this world and created several hybrid people (in different parts of the world) that are developed to a great extent and progressively more developable.
Then they went back to their own world. But they continue to monitor the consequences of their creations and research from afar. Many consider them as gods. And one of them was Mahadev or Shiva. Shivlinga is actually nothing but the symbolic statue of their spaceship!
Unfortunately, most of the descendants of those hybrids or genetically modified humans created in Earth's laboratories without progressing on the path to becoming a sufficiently developed human beings, falling victim to the crooked machinations of an vicious cycle, succumbing to greed, fear and blind faith, they gradually stepping into a terrible deceitful trap called Religion. Deviating from the path of mind development and knowledge leads to destruction.
All this did not escape their notice. They know very well that their research failed.
They wanted to create humans with advanced consciousness but unfortunately monkeys were created instead of humans! Just waiting for time. Soon they are coming back to earth. But this time they are coming back to earth to destroy their creation that did not meet their expectations, that ignorant and blind-believing misguided people. And they want to start a new chapter again!