Sin, seizing its opportunity through the commandment: The word opportunity is a military term for a position seized in enemy territory that becomes a base of operations (see 7:11). By expressing God’s demands, the commandments provoke rebellion within people controlled by sin. God's commandments become a chance for sin to achieve its harmful goals.
apart from the law, sin is dead: The law, by plainly expressing God’s will, makes people more accountable than they would be without it. The law of Moses did not solve Israel’s sin problem but revealed and made it worse. This is always the effect that God’s law, by itself, has on people controlled by sin.