Jesus's parable doesn't just teach us to be persistent in prayer, but persistent in a kind of prayer: justice against her opponent. The church should pray for justice against sin, death, and the devil because that is the only kind of prayer that needs persistence even until the end of time. When Jesus comes back, will he still find people that want to shelter the orphans and clothe the naked? Will you still be shaking your fist at the just judge because you know he promised to be the God of the poor? That's what God wants from us.
