Ministry is Extravagant (or so it would seem)

It's been occurring to me lately: Ministry is extravagant, from anything humanity can actually physically assess. There's nothing we can point to that can prove that ministry is worthwhile. This is on my mind because our church leadership has made a ministry decision that for our little church is somewhat extravagant--from our perspective. Of course, none of us really can measure the eternal good that our actions might take, what enormous fruit that obedience to God might bear. That usually doesn't become apparent in this life, but hopefully in the one to come. Even with this in mind, I've gone back and forth in my opinion about our church leadership's decision; but even indecisive as I am, I tend to think the better decision is the more expensive one.
We all decide what to do with our time, money, belongings, relationships, opportunities of various sorts--sometimes we choose to invest in the present day. Sometimes we save for our own futures. Sometimes we waste our resources in ways that don't bring any return of any beneficial sort. Sometimes we make a sacrifice in faith that God is working in our hearts to accomplish His will. His will has to do with eternal things, with the salvation of souls and with His glory being shown on the earth.
But we can't prove that there is any good in doing what we feel is God's will for us. God doesn't write it on a banner for all to see, what choice He wants us to make for His will; He writes it on our hearts instead. If we choose to justify the investments we make to someone who doesn't share our faith, we have to make temporal decisions that we can point to, or they will be dissatisfied. We can never quantify and justify the outcome of a spiritual sacrifice.
Even having a church, and a pastor, would by secular standards be considered extravagant. We can't even prove that God exists. The benefit may show in our lives, but it can't be quantified, and it can't be proven that knowing God is a true state of things rather than our imagination. We know it, we trust and have hope and faith, but we don't have the words that will convince all humanity that it's valid.
It reminds me of Mary, who poured the bottle of pure nard on Jesus shortly before His crucifixion. The difference was that at that time, she had Jesus physically present, vocally approving her work to those around her who doubted. As a result of her sacrifice, Jesus was pleased and the room was filled with the beautiful perfume of her extravagance, probably for days. And Mary's action has been remembered through these thousands of years from that time.
May choices in my life be so extravagant! May I make decisions that I can't validate to all humanity. May unbelievers wonder at what would motivate the things I do! May it cause them to consider God's worth. May Jesus' approval ring in my heart. I suspect that in eternity I will find that my most sacrificial choices are the only good investments I ever made.