There are quite a number of passages which speak of how the righteous are blessed for their righteousness in this life. For example: If we forsake the things of this life for the sake of the Kingdom, we will receive them back a hundred fold (Lk. 18:30). The context here (and in Lk. 12:31) is clearly of receiving physical blessings from God as a result of our dedication to Him. There are prominent Biblical and contemporary examples of this. Godliness not only gives a future Hope, but has blessings in this life too (1 Tim. 4:8). Other relevant references include Lk. 12:31; Dt. 28; Ps. 37:25; 63:5; 84:11; Mal. 3:10. And yet there are a growing number of believers in many parts of the globe who are finding that life in this world is daily getting grimmer: longer hours for lower pay, poor diet, inadequate clothes, no security for one’s family, and especially (and this, I notice, is the worst-felt of all) lack of spare cash for the work of the Lord within their local context. Increasingly, the promises that there will be extra blessing for those who put God first seem hard to believe. Many brethren and sisters do put God first. Their lives are examples of serving God for nothing. But they are not receiving the promised increase in human things, even though they are fully prepared to use these things in the Lord's service. The idea of joy and peace here and now becomes hard to reconcile with a life spent endlessly planning how to provide the bare necessities of human existence.
It certainly isn't because these brethren and sisters don't have enough faith. It is the poor of this world who are rich in faith (James 2:5). There are many other references which teach that the cross comes before the crown: and the crown is only in the Kingdom. Through much tribulation now we will enter the Kingdom (Acts 14:22). The false image of Christianity which exists in our European and African cultures has taught us that if we believe in God, somehow every story has a happy ending. It's easy to think that as Christians, everything will turn out OK in this life- as well as on judgment day. The broken-hearted single sister finds a wonderful brother and they get married, the separated brother and sister come to love each other again and their marriage becomes better than ever, the unemployed brother gets a nice job after his baptism, the alcoholic finds the Truth and never touches another drop. But the Bible record is packed with examples of believers whose lives, on a human level, didn't have a happy ending. And our experience shows the same. The single sister struggles on all her days of tribulation, faithful to Christ Jesus, and dies alone in her bedroom: assured of acceptance by the Lord who loved her and gave himself for her. The marriage rift becomes more serious, the wife leaves the faith, divorces, and marries again. The brother holds on, 'does the readings' alone in his flat, night after night, walking that Kingdom road with an incurable pain in the soul. The unemployed brother gets thrown out of his home, his wife leaves him. And he struggles on in faith, until at last the Lord comes to end this petty life. Of course, there are other examples of where God abundantly provides materially, He honours His promise to provide physical blessings for His children. I openly, and gratefully, admit that compared to many of my brethren, this is the category I come under. But very often, this doesn't happen: especially, it seems, in Africa, Asia and Eastern Europe at the moment. Life for many brethren and sisters doesn't seem to be heading towards a happy ending, a walking off into the sunset with the promised hundred fold of blessings. Why? Why? Does a man serve God for nothing?
Personally, I put this on my long list of irreconcilable paradoxes in God's dealings with us (1). There are verses which teach that God will materially bless us in this life. And there are others which say that the reverse is true. Yet God's word is without contradiction. Job, David and Asaph were among the many believers who wrestled the same paradox. They all ended up accepting it. But they offered no trite answer to it, no pithy few sentences that explained it.
(1) See The Inconsistency Of God for fuller discussion of this.