Seeing that faith is required, why do you say that they are given to confirm us in faith, to assure us of the promises of God?

It is not sufficient for faith once to be generated in us. It must be nourished and sustained, that it may grow day by day and be increased within us. To nourish, strengthen, and increase it, God gives us the sacraments. This is what Paul indicates when he says that they are used to seal the promises of God in our hearts (Rom 4:11).