Scripture records several enemies encountered by the children of Israel as they traveled from Egypt to Canaan. To name only a few:
- Pharaoh and the Egyptian army (Exodus 14:4–9; 14:30–31)
- the Amalekites (Exodus 17:8–16)
- the Canaanites of Arad (Numbers 21:1–3)
- the Amorites (Numbers 21:21–31)
We rightly recognize that these enemies parallel the enemies of the Christian today. Of course we don't fight against flesh and blood (Ephesians 6:12) – our enemies are no less real, but they aren't visible to the human eye. I'm old enough to remember preachers who used to talk about "the world, the flesh, and the devil": I'm not entirely sure that's a complete list either, it seems to me Ephesians 6:12 goes a little further than that. Nevertheless, we are in conflict just like Israel was in conflict.
We can think of the enemies of Israel as three general groups. The first contains Pharaoh and his army. That was a terrifying enemy, and Israel was explicitly told not to fight them: the command was "Fear not: stand still, and see the salvation of Jehovah" (Exodus 14:13). Then there is the second group, enemies like the Amalekites. There was real battle with the Amalekites, but there was no utter destruction: Amalek's power was broken (Exodus 17:13), but there was the promise of perpetual war with them (Exodus 17:16). Finally, we might think of the third group as being like the Canaanites of Arad: the Lord gave Israel victory over them in a single decisive battle, they were utterly destroyed.
In broad terms, we have those same three types of enemy. It's striking that when Scripture talks about sin (as opposed to "sins", the principle, not the specific transgressions), it uses the language of deliverance. I'd guess that every believer has prayed for victory over sin, but I can't find a single place where Scripture uses the language of victory when it talks about sin. Scripture talks about deliverance in relation to sin, not victory. Israel wasn't victorious over Pharaoh, Israel was delivered from Pharaoh (Exodus 14:30).
The New Testament uses similar language when it discusses the flesh to the language used to discuss Amalek. Amalek's power is broken, but the conflict is still perpetual. The flesh is still there in us: it's power is broken, but there is ongoing conflict (Galatians 5:17).
I suspect our "members on the earth" (Colossians 3:5) fall into this second category. I suspect they aren't ever really gone, although their power over us may be broken. And while we are called to put them to death, I'm not sure they ever quite die. I'd be interested to hear people's comments on that...
It seems to me the specific habits of the flesh (Colossians 3:8–9) fall into the third category. There is very real conflict with those things, but we don't see war from generation to generation like with Amalek. The epistles differentiate between the flesh and its habits. We won't be rid of the flesh until the Lord Jesus changes our vile bodies (Philippians 3:21), but that's not to say its habits are here to stay. Indeed, Galatians 5:16 seems to indicate the opposite.
But the real point is, we need to know our enemy. We need to have the spiritual discernment to understand when we're called to "stand still and see the salvation of Jehovah", and when we're called to pick up a sword and charge at the foe.