When we lose sight of this we think of the early church as a group which quickly figured it all out - right belief, right practice, perfect community - and then assume that we simply must return to that time period (somehow) and we too will have everything figured out. Therein lies one of the most glaring distinctions between the modern and ancient churches: while we so often believe that we have the Spirit in our comprehension, the first believers knew that it was impossible to properly understand (much less systematize) the holy Spirit of God. And so we are doing church in a much different context than it was ever intended to be.
Church leadership expert, Reggie McNeal, suggests that we must "change the scorecard" of how we understand and evaluate our church culture. He is right on this, for the taming of the Spirit in the contemporary expressions of church is the primary reason for the current failures of the church. One example of this may be found in the overly used "track record" for evaluating leaders within the church. The phrase indicates a search for some sort of measurable criteria by which one's ministry can be evaluated. In other words, this is a tracking of success within the field of ministry. And because such tracking needs to have "objective criteria" it doesn't take too long for it to be a Christianized evaluation of worldly triumph.
If we are to believe that the Spirit of God is untamable and unstoppable, then we must accept that no single criteria can be used to evaluate the Spirit's activity. Spiritual gifts inventories can only go so far, numerical growth can only show so much, and churches that are run simply as business with an opening and closing prayer doesn't cut it. The real mission is the spark which is set off within the heart of an individual and community that fuels passion and gives purpose to the work of the kingdom of God.
And that will make us all begin to look like Jesus. Radical. Bold. Loved. Despised. Jesus.
It seems to me that this fruit is the only measurable presence of the Spirit, that we should have the love of Christ being poured out as Christ into all the world (with all the defining features of joy, peace, forbearance, kindness, goodness, faithfulness, gentleness and self-control). And in a quest to become Christ in the world we have no hope of catching up, though we are blessed to be able to run hard after him and spread his work around as we go.
So, among other things Pentecost is a powerful reminder that we cannot keep up with the Spirit of God. The book of Acts is a demonstrable reminder of that.