Even murder can be forgiven. Paul's was forgiven for his participation in the murder of Stephen. Paul admitted that his vote helped kill the innocent. But God saved Paul because he was willing to confess and forsake his sin. The issue is not whether a murder can become a Christian, but can a murder be forgiven.
Love is both positive and negative.
We know that we have passed from death to life, because we love our brothers. Anyone who does not love remains in death. Anyone who hates his brother is a murderer, and you know that no murderer has eternal life in him. Christian love is personal and active. The parable of the good Samaritan is a story about loving our neighbor.