But you, beloved, building yourselves up in your most holy faith and praying in the Holy Spirit, keep yourselves in the love of God, waiting for the mercy of our Lord Jesus Christ that leads to eternal life. And have mercy on those who doubt; save others by snatching them out of the fire; to others show mercy with fear, hating even the garment stained by the flesh. (Jude 21-23)
I'm chewing over this passage in Jude at the moment. There's plenty of meat here, and I'm sure there is more to get out of it, but here's what I've got so far...
The first point of note is that this is one of the trinitarian passages in Scripture. [My friend Matthew has been pondering some more of these] All three persons of the Godhead are mentioned in the process of how we build ourselves up in the faith. And of course since we are to build ourselves up - we are too! The outworking of our faith is a cooperation between the human and the whole of the Divine.
The threefold God gives us a threefold pattern of how to build ourselves up in the faith: pray in the Spirit, remain in the love of God, wait for the mercy of Christ. There is a common theme of abiding here - all of our activity is to come from a place of peace and intimacy in the presence of God. It is the one thing that is necessary; the one thing that we must find and hold; the one thing that we must never allow to be taken from us.
But abiding in God is never a passive activity. These three things are dynamic and powerful.
Praying in the Spirit touches the heavens and changes the earth.
The love of God cannot be in us without causing us to express that love towards others.
Waiting on Christ is not passive either; indeed Peter says we wait for and hasten the day of his coming. Waiting on the mercy of Christ causes us to outwork that mercy towards others.
Mercy on those who doubt. If we are strong in the faith, because we have built ourselves up, it is so we can build others up too, not so we can tear them down.
Mercy on those who are lost. Extending the mercy of Jesus that leads to eternal life to others - snatching them out of the fire that God wants none to perish in.
Mercy on those who sin - but a mercy mixed with fear and loathing - not towards the sinner but towards the sin. Mercy towards the sinner should never involve condoning or compromise with the sin.
If we rest in the place of intimacy with God we will be a joyously busy built-up people indeed!