Doug Wilson posts a great reminder and encouragement in Because Snakes Don't Have Feet.
The Bible consistently speaks of leaving the old way of life in terms of leaving the way of envy. Sins are like grapes, which means that they come in clusters, and so other things are consistently mentioned as well. A number of our sins do come in bundles. But one of the things we must learn is what a deadly toxin envy is. It is one of the things that contributes heavily to the poisonous way we used to live.
"The night is far spent, the day is at hand: let us therefore cast off the works of darkness, and let us put on the armour of light. Let us walk honestly, as in the day; not in rioting and drunkenness, not in chambering and wantonness, not in strife and envying. But put ye on the Lord Jesus Christ, and make not provision for the flesh, to fulfil the lusts thereof" (Rom. 13:12-14).
Not in strife and envying. Putting on the Lord Jesus Christ as our armor means that we are making no provision for the flesh. In this passage, the flesh involves partying, sleeping around, and envious snark. These are the works of darkness that we are to "cast off," and we are to replace them with the armor of light -- which means putting on the Lord Jesus. When Paul talks about the armor of God elsewhere, we can see that not only is Jesus the whole armor, He is also every piece of it. We put on the helmet of salvation, and Jesus is our salvation. We put on the breastplate of righteousness, and Jesus is our righteousness, and so on.
One of our problems is that for the most part conservative churches do know how to cast off the wantonness and associated wildness. We look askance at people who want to call themselves Christians and still whoop it up at the saloon. But Paul says to put away all strife and envy, and he includes them in that toxic mix. To give up sex, drugs, and rock n' roll, but to keep the envy, is surely a bad deal. That is like surrendering the golden Babylon orgy goblet in order to drink the poison out of a modest little Dixie cup.
The center of what God attacked in the cross was the pride and envy of our foolish race. Jesus was delivered up on account of envy, and His death was the death of envy and accusation. But His death was the death of all of it everywhere, and not just envy out there among the non-Christians.
This is why Christians are told to keep it simple. When it comes to evil, when it comes to accusation and envy, we are told to be simple. Good has layers and complexities which we may search out as we please, but when it comes to evil we are to recoil with a simple bleccch.
"I am glad therefore on your behalf: but yet I would have you wise unto that which is good, and simple concerning evil. And the God of peace shall bruise Satan under your feet shortly. The grace of our Lord Jesus Christ be with you. Amen" (Rom. 16:19-20).
"The God of peace will soon crush Satan under your feet" (Rom. 16:20, ESV).
We are a key means that God uses frustrate the works of the devil. The phrasing here is ironic and glorious. The God of peace will crush Satan. This is no contradiction. Either crushing peace destroys accusation, or crushing accusation destroys peace. There is no other way.
If we have put on the whole armor of God, our feet are shod with the gospel of peace (Eph. 6:14). What do feet shod with peace do? They crush accusations, that's what they do. They crush devils; they walk on snakes. We have put on the Lord Jesus, and that does not mean we put on all the armor except for the shoes. We are not outfitted with the panoply of orthodoxy, but then rush out into a field of vipers barefoot. The God of peace will crush all opposition, and He intends to do it with the feet of His people.
But we cannot be shod with this peace and walk on snakes if we are snakes. Because snakes don't have feet.