Why did it take so long? -Questions about Jesus, the Old Testament, the Messiah and Salvation as we think of sharing our faith.

When I began to prepare to lead my Fellowship through Matthew I was hoping to approach it afresh for myself.  That has certainly been the case.   Right from the opening words of Matthew and the genealogy of Jesus I was asking some new questions.
This really is Matthew's introduction of Jesus.  If these are the very first words, they must be important.  The genealogy is full of many great names, each that conveys an amazing and important story.  In particular, Abraham and David take a prominent role and the whole genealogy is even structured around them, as well as the Exile.   Matthew is very careful to trace Jesus to this long history of Israel,  the covenants and promises that God made with both Abraham and David, the Exile and down to the time of Jesus.  I remember thinking, how is the way that I have been inclined to introduce people to Jesus been different than this.  Do I introduce Jesus by tying Him into this longer history and this much greater story that traces itself through the entire scripture?

Interestingly, as I led someone else through the passage they asked a great question..."why did God take so long?"  We were talking about Jesus and salvation and what this person meant was, if the answer to the problem of sin introduced in the first chapters of Genesis was Jesus- His atoning death on a cross, and His resurrection, why did God wait so many thousands of years and so many generations to send Him?  Again, I was recognizing a bit of a disconnect from the way Matthew introduced Jesus and the way we often speak and explain Jesus.  I suggested two possible responses:
 a) That God is God and gets to decide what He does but we can trust that His choices are always best (true enough but that does not really satisfy the intellectual inquiry!)
b) I pointed out that the understanding of Jesus, the cross, the substitutionary atonement and sacrifice that we find in the New Testament all uses the Old Testament story as a reference.  Without that history, could we ever really understand what Jesus did for us and thus be able to respond?  I recognized, however, that there was probably more that I could share and a fuller understanding that I could be offering.

Interestingly, shortly after I heard about the release of a book by Scot McKnight entitled The King Jesus Gospel.  (I don't even remember where I heard about it - perhaps Ed Stetzer's blog?) It seemed to address some of the questions I had been asking.  It was a helpful and an interesting read.   McKnight goes on to demonstrate how many of our methods of sharing our faith, evangelizing or introducing Jesus skip right over almost the entire New Testament.  More often than not, they hit the problem of sin and jump right to the sacrificial offering of Jesus as penal substitution.  He points to a number of evangelistic sermons in Acts that take a different approach and delve into the whole history.   Of course Jesus and the apostle's were preaching to a very Jewish audience steeped in Jewish religion and expectation to whom the history and Jesus' being the Messiah and King would have been paramount.  McKnight does reference later sermon's by Peter and Paul to gentiles, however, that also touch on this history.

The one question, however, that I still have (and maybe I just read the book too fast and missed something - possible) is so what?  Does it really matter?  Why did God take so long, and why should it matter to our sharing of faith?  I would love some help with this one, and any thoughts that you might be able to contribute to the discussion.  Here are two thoughts as to why it might matter that I have come up with:

1)  That is how it is done biblically.  Again, a somewhat intellectually unsatisfying response but maybe important none the less.  When in doubt,  do it as closely to how it is done in scripture as possible as I investigate further.

2)  When we remove salvation from the greater story of the Bible, ranging from Genesis to Revelation, then we miss understanding some of the greater points of living as Kingdom citizens.  We can see that "being saved" is not the end but rather the beginning of our Kingdom citizenship.  We can see the unique roles and responsibilities we have here and the place of the church to be a foretaste of the kingdom.  We can better understand the mission of the church as we exist in this time between Jesus' Ascension and His return. We see our place within this grand story of God's redemption and we can be encouraged to play our role within the drama that is unfolding around us.  I think that this one point is suggested by McKnight.  

That is what I have come up with but I would love some further insight, thoughts and suggestions.  
Then maybe next is the application of the insights!