Joshua may not be the first figure you turn to in the Old Testament in order to understand mercy and compassion. The Book of Joshua is bloody and violent. However, even in his name, Joshua prefigures Jesus and there is much in the book that soberly tells us about God's love and mercy if we read it right. To say that the God of the Old Testament is somehow different to the God of the New, that love and forgiveness are to be found only in the New is the heresy of Marcionism and must be avoided at all costs. Christ is the same, yesterday, today, forever (Hebrews 13:8).
The musing that follows is about what Joshua teaches us with regards to Communion for divorced and remarried Catholics and those who openly flout heresy within the Church.
The treatment of the inhabitants of the promised land at the hand of the Israelites seems incomprehensible to us. None were to be spared. How can this be compassionate? Well, God has set up a covenant with His people. It goes without saying that God will keep his side of the covenant. It is us, His children, who will, left to our own devices move away from that covenant, dilute it, infiltrate it with false teaching and ideas, feeling that God is not fulfilling His side of the covenant, losing our trust in Him, turning Him into something He is not (fickle and moved by the times). Contact with the Caananites represent that tendency within us to dilute the faith, to distort and disfigure all that is good. It is that which we must cut out at the root. Christ tells us as much in the New Testament too.
In chapter 9 of the Book of Joshua, along come the Gabaonites. They, fearing for their lives, trick Joshua into sparing them. They pretend to have travelled a long distance, to be weary and desolate, they throw themselves on the mercy of Joshua and he swears an oath before God that they will be spared. Now oaths always seem to be a bad thing in scripture (something to regret) because they must be kept. [ As an aside, surely the biblical precedents against oaths, should have been enough to make St Pius X see that getting priests to swear the Oath Against Modernism (no matter how well motivated) was a bad thing. The backlash it created was certainly harmful and I do believe that the oath did more harm than good. But this just goes to show that Pope's don't have to be wise to be Saints.]
The Gabaonites had deceived Joshua, but he had to spare their lives because of the oath. They were put to the service of the Israelites, hewing wood and carrying water.
Now, Christian marriage is a covenant between a man and a woman and God. We are people of that covenant. Holy Communion is a covenant too and it comes quite rightly with preconditions. God can't break covenants, but we in our stupidity think we can. We cannot dilute a covenant, we can not change its essence. If some claim that the Church is not merciful for denying certain people Communion, and therefore that the Church is out of step with God, are they not then like the Gabaonites. Are they not therefore asking for mercy as outsiders with little understanding of the faith? Now, will the Church, like Joshua, give them mercy and give them what they want irrespective of their motives, assuming the purity of their intentions. Surely if She does, then the modern day Gabaonites must be willing to be at the service of the Church in the most unglamourous of ways (the hewers of wood and carriers of water) and if they are not willing to give such service, then surely their motives must have been corrupt from the start.