Notice that the verse speaks of murderers and idolaters, rather than the acts of murder and idolatry. The difference is that the first describes the man himself, while the second describes something that he does. Since every evil man would like to distance himself from the things he does and deceive himself that he remains unaffected in his heart by such sins, the verse reminds us that we cannot sin without our innermost being changing in the profoundest way. Sin is like some foul liquid put inside a pure vessel. It stains the vessel, spoiling it for all future use. Some of that stain taints the next liquid poured into the same vessel, even though it is pure.
Do we have a light view of sin? The verse shows there is an inseparable connection between a man’s conduct and his destiny. It is no small thing to yield to sin. To do so is to take the first step in a journey that leads to a place where none would ever wish to go. By contrast with the those who overcome, these are overpowered by enemies too strong for them and dragged down to hell forever. Do men really consider the consequences of what they do on earth as they should? A man must now be what he intends to be forever. The children of the light are to live as if the day had already come. Let the children of darkness realise what they are preparing for themselves, or else let them turn from their sin forever and throw themselves on the mercy of the Lord.