I don't think that he was ever truly "evil", nor even the idea of 'Kira'. Light merely fell to the consequences of striving for absolute power and 'Kira' as the entity he saw, an idea that was originally brought up by believed good intention, twisted and confused his morals when he let it absorb him as a human being. No, he wasn't "evil", he was actually horrendously human throughout, despite how his dastardly actions in the latter half of the series may have made it seem.

A lot of anime really blurs the lines between good and evil, and I feel Death Note does that better than most. It's not that Light/Kira does not have any elements of what could be perceived of as "evil" in him, and he certainly looks at the world from a utilitarian perspective more than anything, viewing the ends as justifying the means. Deontologically, one could certainly view him as evil, or at the very least malicious.

While i don't agree with Light's actions, to his own mind he was the hero of mankind. In the end his unkind actions came from a kind and caring place. He just wanted to make the world better.

i'm still not sure about this but i think the fact that he killed millions of people is evil, but then again... his intentions were pure so he's not entirely bad i guess ._.

He is not that evil, he just wanted to cleanse the world from evil. Although his actions went insane later on.

No he want to make a revolution and change he have good intention but he let power and judgement upon others corrupt him and consumpt with power which let him to completely lose him mind and moral but he did at first have good intention by wiping criminal and bringing peace in his own way

I think he is misguided and had good intentions but his goals were evil. I'm sympathetic. He was tyrannical and merciless. He wanted a world where only honest and caring people live but 'he' wasn't even caring (I can excuse he's dishonesty if he was using it to bring true justice so I wont criticize that); *spoiler* he would kill his father and sister and remorselessly manipulated Misa. He didn't have love or compassion for anyone, he smiled at * * * * spoiler * * * * Lawliet's death. Why does he even want to make a world where only caring and honest people live even when he wouldn't understand kind and caring people. Maybe he's just obsessed and misguided, as opposed to shamelessly /intentionally being evil as *spoiler of first few episodes* He was offended when "L" said that what Kira was doing was evil, so I think that means Light doesn't realize that what he's doing is evil.

both

Why would he not be evil?

In my opinion, Light was never evil. He simply let his opposition and his desire to create a perfect new world get the better of him. At the very beginning of the anime, he seems like a normal person; very smart, popular, and social. Finding the death note and choosing to create a new world could be symbolic of Light's death right then and there, because after that, nothing else mattered to him. He would kill anyone and everyone that got in his way, he would lie and manipulate others, and think nothing of it. All in all, Light wasn't evil, the death note was.