Read Romans 6:15-18
Talk about being a slave to something: You can be a slave to only one thing, sin (aka the world) or God. These rules are set by God. There are no exceptions.
Ask about being a slave to sin: What does it mean to be a slave to sin (aka the world)? Slave to God? On what side of the spectrum do you lie?…Once you put your faith (belief and trust) in Jesus, you are a slave to the righteous living (aka slave to God).