Ramayan

Brahama, vishnu, mahesh are the only three core gods in world. Remaining are various shades of these three. These three gods has help lanka pati Ravana to become very powerful so that no one can beat him, even these three god himselfs. Ravan is very powerful and he always use to misuse his power for bad works like disturbing hrushigan during their 'whomehavans' all on earth totally distubed because of rakshas behavior. Lots of shreshth hrushigan went to lord vishnu with loard brhma and mahadeva too. Request them to do some thing to help them all from ravanas rakshas behavior. So lord vishnu decided to go on earth to kill all rakshas on earth and ravana too.

Ramayana is one of ancient indian epic poem written by hrushi valmiki as script 5000 years back. As per script written ramayana has to be produced so every thing happen in ramayana according to written script of valmiki hrushi. It has involvement of various gods for various reasons.