For the sake of your Son, Jesus Christ, have mercy on us.
Mercy, for Jesus’s sake – this is what we are asking of God.
We can ask it because of what Jesus did for us – His willingness to become one of us, to take upon Himself the sin of the world, to die for us. Because of all that He did, we can ask for mercy.
Jesus did those things for us because we could not do them – would not do them – for ourselves, much less for anyone else. Jesus did those things for us because of His great love for us.
Jesus did those things for us because He is the very essence, the very nature, of love.
It is in the name of that love that we dare to ask for the mercy we do not in any way deserve.