Fit how and for what? To be tied?
Fit for life with God. That's something good to be fit for. And fit simply means, "To be suitable to or adapted to," as in, "let the punishment fit the crime."
I'm on the subject of fitness because I'm on the subject of rehabilitation. Rehabilitation is what happens when something or someone is rehabilitated or made fit again.
If something or someone is fit then it is fully what it is and can accomplish what it is meant to accomplish. That is my thinking for linking fitness with function. One more item of clarification. I consider fitness synonymous with theory and function with practice. If a parish is fit, then it is what is supposed to be. If one if functional, then it can do what it is supposed to do.
I recently quoted a contemporary reflection on parish fitness and function. Now I'll quote a few reflections from the 1st century.
What is a fit parish? What is a parish supposed to be?
Two texts quickly come to mind: Ephesians 1:22-23 and 1 Peter 2:9-10
And He put all things in subjection under His feet, and gave Him as head over all things to the church, which is His body, the fullness of Him who fills all in all. (Eph. 1:22-23)
But you are a chosen race, a royal priesthood, a holy nation, a people for God’s own possession, so that you may proclaim the excellencies of Him who has called you out of darkness into His marvelous light; for you once were not a people, but now you are the people of God; you had not received mercy, but now you have received mercy. (1 Pt 2:9-10)
The 1 Peter text includes a reference to function. "That you may proclaim the excellencies of Him who has called you out of darkness into His marvelous light."
Paul agrees with Peter, but with different words: "to the praise of his glory." That's the function of a fit church. "So that we, who were the first to set our hope on Christ, would be to the praise of his glory."
Here is the text in context.
In him we have obtained an inheritance, having been predestined according to the purpose of him who works all things according to the counsel of his will, so that we who were the first to hope in Christ might be to the praise of his glory. In him you also, when you heard the word of truth, the gospel of your salvation, and believed in him, were sealed with the promised Holy Spirit, who is the guarantee of our inheritance until we acquire possession of it, to the praise of his glory. (Eph. 1:11-14)
I have a few things to write about this. But what Peter and Paul wrote is far more important. So their words are enough for now.