Before I get into the 1 John text comparing the world hating believers with a believer hating another believer, I'm looking for an answer to this question I posed:
Why wouldn't the Spirit keep believers from committing any kind of sin? Are there some sins of believers that are permissible to God, and others that are strictly off limits?
All sins are off limits.
However, man chooses to do things according to his nature.
When a man is regenerated by the Holy Spirit he is given a new spiritual nature that is free to do godly things and can see and discern spiritual things. A man with that nature naturally believes in Christ and chooses to repent. A person who repents is indwelt by the Holy Spirit.
WHen a person has a new spiritual nature and is indwelt by the Holy Spirit of God he is a new creature. He loves God and hates sin.
However, until he is shed of his body he will still fight against the dead and sinful flesh, so during the proces of sanctification that is lived out post justification the saved person will still stumble into sinful behavior now and then. He will, however, be convicted of it and it will grieve him and he will choose to repent.
However, given even that, there are simply some things that are so wicked and contrary to love that a person who has a Spiritual nature and is indwelt by the Spirit will not do. Murder and hatred of ones brother are explicitly mentioned as examples of things that a saved person will not do.