The three “theological virtues” are faith, hope, and love (1 Corinthians 13:13). What is the relationship between these three? And how do they play out in the Christian life?
Martin Luther explores these questions in an absolutely stunning sermon on Christ’s healing of the ten lepers (Luke 17:11-19). Read how it concludes (my bolds). From Martin Luther, The Ten Lepers, 14th Sunday after Trinity, Luke 17:11-19, from Church Postil of 1521:
81. And in conclusion we observe that this Gospel sufficiently teaches and represents the entire Christian life with all its events and sufferings; for the two chief things are faith and love. Faith receives the good; love gives the good. Faith offers us God as our own; love gives us to our neighbor as his own. Now when such life begins, God goes to work and improves it by trials and conflicts, through which a man increases more and more in faith and love, that through his own experience God becomes to him so heartily dear and precious, and he no longer fears anything. . . .
82. How beautifully he divides the three principles, that faith goes forth in trusting, love in laboring, and hope in patience and suffering. As though he would say: Your faith is not a dream nor a fancy, but it is life and action; and your love is not passive nor is it idle, but it serves well for your neighbor. All this takes place in prosperous days, while your hope is exercised in suffering and patience, and all this in Christ; for there is no faith, nor love, nor hope outside of Christ, as I said above. Thus a Christian life goes through good and evil until the end, and yet it does not seek revenge, and only grows more and more in faith, love and hope.83. And love, which naturally follows faith, is divided into two parts: it loves God, who does so much for her through Christ in faith; it loves its neighbor, and does to him, as God does to her. Therefore, all the works of such a man go to his neighbor for God’s sake who loved him, and he does no work relating to God except to love and to praise, and he confesses this freely before the world. For God does not need other works. Thus, all worship is with the mouth; although that is also called a service of God which is done to our neighbor. But I speak now only of the service rendered to God, in which the one part man can take is to love and to praise; but in this he must resign himself wholly and entirely in all adversity. Behold, what more would you know as to how to be a Christian? Have faith and love, continue in these, then you have and can do all things; the rest will all be taught and given to you without any exertion on your part.