Surely discussing how many angels can dance on a pin's head is a waste of time. But what about considering for a moment the impact of Jesus' cross upon them?
Recently I was chewing upon Colossians 1:20, where it says that God was pleased through Christ "to reconcile all thing to Himself, having made peace through the blood of His cross; through Him, I say, whether things on earth or things in_ heaven_." That last phrase puzzles the Bible student. Jesus' cross reconciling things on this sinful earth one can understand. Yet how did it reconcile, or make peace with, things in heaven?
To make sense of this phrase, many commentators offer different suggestions of what the "things in heaven" are, from Jews to glorified believers to God Himself. None of them are satisfying or clear. But how could it be that the angels in heaven needed the peace and reconciliation the cross offers? Consider the incredible insight of John Eadie in his Commentary on the Greek Text of Paul's Letter to the Colossians:
_There needed no atonement for innocent creatures (i.e. non-fallen angels), but they must have felt the disruption of sin, and seen the terrible anger of God against it. May they not have trembled at the bare idea of apostasy, and may not the very suspicion of it have made them stand before God with more awe than love? When the angels beheld their fellows sin so grievously, when they mourned over the tarnished brightness of their lost and exiled natures, might not the memory of the melancholy spectacle fill them with terror, and as they felt themselves placed in a jeopardous crisis, might they not shrink as they gazed upon the unsullied justice, and inexorable vengeance of Jehovah-king? Might no holiness unrelieved by an act of grace, be ever impressing the conviction that “it is a fearful thing to fall into the hands of the living God?” __
...But when they found the ineffable stores of Divine benignity towards man…in a vast salvation secured at a vast expense, and in a happy alliance concluded between them and the ransomed church – did they not share in the same reconciliation and feel themselves drawn nearer a God of grace, whom they can now love with a higher thrill and praise with a more rapturous hallelujah? In being reunited with man they feel themselves brought closer to God, and though they sing of a salvation which they did not require, still they experience the Savior’s tenderness, and are charmed with the reign of his crowned humanity…Gabriel embraces Adam, and both enjoy a vicinity to God, which but for the reconciliation of the cross would have never been vouchsafed to either….Blessings which naked Deity might not be able to bestow are poured out upon them by the incarnate Lord “who fills all in all;” and the exhibition of love in the agonies of Christ may have secured what unalloyed equity could not, may have placed the universe for ever beyond the reach of apostasy and revolt.
As false teachers in Colossae were promoting a bizarre doctrine that included a hierarchy of angels aiding in the process of redemption, making the angels objects of worship (Colossians 2:18), Paul counters with just the opposite. The angels, these holy and sensitive creatures, are themselves in need of reconciliation. They did not need to be saved from sin that they do not possess. Rather, as Eadie points out, they needed to be granted the further knowledge of God the cross reveals in order to have a perfected peace necessary for living eternally in His presence. They have received this in witnessing how the Lamb that they adore has treated us.
Perhaps this sense of this verse will give you further appreciation of other ones involving angels. For instance, when you read in Luke 15 of how the angels rejoice when one sinner repents, perhaps you like I have thought of it as somewhat similar to football fans in a stadium rejoicing over a player scoring a touchdown. Sure, they are happy that their side is winning the victory, but they do not have the same vested sense of thrill as being on the field would bring. Yet given what Colossians 1:20 teaches us, perhaps this truth needs to be understood in a more personal way for the angels. As the angels see Christ rescuing yet another sinner, may not their cheers be more like an army witnessing a war hero sacrificing his well-being to save another? They are happy for the redeemed sinner, but they also themselves feel safer, protected, drawn closer to the presence of the glorious Lord of hosts. Watching the love that God has for weak and foolish creatures like us helps make the love of God more real to these magnificent beings.
No wonder our salvation consists of "things into which angels long to look" (I Peter 1:12)!