What is Citizenship Amendment Act (CAA) 2019? Why was it required? Why are Jihadist/Western Pseudo-Intellectuals Opposing it?

Citizenship Amendment Act 2019 is criticized by Jihadists, Racists and western pseudo-intellectuals without even understanding what the bill is all about and what the bill is actually doing. In order to understand the reason of opposition lets first understand what CAA 2019 is all about.