The Missing Pieces of the Puzzle

I want to be loving towards everyone and love God but lately I smoked marijuana and that made me realize the deep core essence of my personality being is evil, and that bad things I do are manifestations of my true, evil, nature. I’ve been wanting to fight with people, whenever someone knocks my door I grab my knife for protection, and I don’t think people who call themselves "Christian" are truly Christian. How do I change my personality and become a good person? I want to be closer to God.