All three of these words are absolutely critical in our understanding of God and our faith. Grace, for example, is the good that God gives to us that we don't deserve. In Acts 17:25, we learn that God "himself gives everyone life and breath and everything else." What God gives to us includes our very next breath. Even in our darkest hour, all we need is given by God so we can endure.
Mercy is the bad that God withholds from us that we do deserve. In Lamentations 3:22, we read, "Because of the Lord's great love we are not consumed." Even when we go astray, God loves us and helps us turn back to him.
Peace is what God brings to his people. Jesus said, "Peace I leave with you; my peace I give to you," in John 14:27. Even in the worst of times, it is possible for us to have an inner tranquility when we come to the realization that God is in control.
To these words I would add the word Hope. This, as most of you know, is probably my favorite word. To me, Hope means that no matter what the circumstances, no matter how dreary the outlook, God gives us the assurance that a great future is coming. I love the way it is expressed in Romans 5:3-5: "We know that trouble produces endurance, endurance produces character, and character produces hope. And hope doesn't disappoint us, because the love of God has been poured out in our hearts through the Holy Spirit, who has been given to us."
We can be encouraged that throughout our lives God will give us the grace, mercy, peace, and hope that we need to live.
Grace (and Mercy and Peace) and Hope to you,