(Kadamba Kanana Swami, 14th September 2012, Lecture: CC Madhya-Lila 13.1-8, Pretoria, South Africa)
It’s not difficult for Krsna to kill demons, that’s obvious. He is all powerful so he can do whatever he likes. The only reason why he personally kills demons is to give faith to his devotees. Krsna doesn’t have to do that either… if he wants then all the demons just disappear, right! That’s easy but he kills demons personally so that his devotees can say that he is protecting us! Protecting his devotees, to give faith to his devotees.
But obviously, Krsna also likes to have some demons around sometimes, just for fun. He’s very powerful and very strong so sometimes he needs to have a bit of a wrestling match, to beat up a few demons!