Luke 2:11, a son is GIVEN
Isaiah 8 closes with a picture of awful gloom and judgement and chapter 9 opens with a glorious passing of the night and the rising of the sun with the darkness banished. The prophet then describes a glorious future and in 9:6-7 gives the ground on which that future is based, "For unto us a child is born unto us a son is given…The zeal of the Lord Almighty will accomplish this."
For unto us a child is born says why the future will not be like the past. "Unto us a son is given"—he is a gift. A gift! Not something we merit; we didn't earn him. He was sent by God as a gift. We didn't come up with him, didn't mould and shape him to suit our needs; we can't claim in that sense that he is "one of our own". He came from God! And though it is profoundly true that he was altogether one of us and because we dare not offer ourselves before the Holy Father we offer Jesus—though all that is true Jesus is not our gift to God he is God's gift to us!
Our salvation, our hope, our life are all wrapped up in Jesus who was given to us as a gift from God. Salvation begins and ends with God. It doesn't begin with our believing but with God's gracious purpose to save us before times eternal which when brought to us in the gospel generates faith in us (Philippians 1:29). Speaking of God in 2 Timothy 1:9 Paul says, "Who has saved us and called us to a holy life—not because of anything we have done but because of his own purpose and grace. This grace was given us in Christ Jesus before the beginning of time."
God saved us not because of anything we have done! God saved us because of his own purpose and grace! This grace was given to us! This grace was given to us before the beginning of time. This grace is experienced by us here and now.
Before we wrestle with the difficulties that such talk generates, the proper thing to do is confess the truth of it! If it's the case that we are saved then we should thank God that we have been saved because he purposed it in grace through Jesus Christ before the beginning of time. It's all right, don't you know, to be gob-smacked by this and it's all right to say, "How does that work?" because it's only when we take the passage seriously that we're overwhelmed and bewildered with a glad bewilderment.
Some of us aren't in the least staggered; we have it all worked out; we can easily "explain" and with very little effort (quoting a verse here and there and constructing a little syllogism here and there) we can plumb the depths of such truth. But I'm sure that says more about our ignorance than about our understanding and maybe it says a bit about our sense of our own brilliance.
No, the son in the manger is given to us, the prophet said. "Today in the city of David a Saviour has been born to you; he is Christ the Lord," says the angel in Luke 2:11. A Saviour has been "born to you" is the angels equivalent to Isaiah's "a son is given."
Whatever the mystery here or the difficulties that need to be worked out, this we know: our salvation didn't begin with us! Our salvation was purposed before we came along. God didn't look down the ages to see who would receive him and then say, "I purpose to save those whom I foresee are willing to receive me." God purposed to save, sent his Son to save and the Spirit brings the gospel to save. When we happily, joyously find ourselves saved we know we have freely responded to God's eternal purpose. We know then that unto us a Son was given.