This dual salutation is found in all the Pauline letters (with "mercy" add in 1 Tim. 1:2 and II Tim. 1:2). Grace is the divine favor showed to man, and peace is that state of spiritual well-being which follows as a result. More than a casual greeting, it bestows what it proclaims. The Book of Revelation NICNT (Grand Rapids, Eerdmans: 1977) 68

How can he abide long time in peace who occupieth himself with other men's matters...?

A great many people are trying to make peace, but that has already been done. God has not left it for us to do; all we have to do is enter into it.

A true Christian is one who has not only peace of conscience, but war within.

He that is not a son of Peace is not a son of God. All other sins destroy the Church consequentially; but Division and Separation demolish it directly...

Our peace and confidence are to be found not in our empirical holiness, not in our progress toward perfection, but in the alien righteousness of Jesus Christ that covers our sinfulness and alone makes us acceptable before a holy God.

If we have not quiet in our minds, our outward comfort will do no more for us than a golden slipper on a gouty foot.

If war is ever lawful, then peace is sometimes sinful.

Tolerance is, no doubt, a virtue without which none of us can live; but we must, nevertheless, at least understand that it is, strictly speaking, destructive of fellowship, for it is a gesture by which the divine disturbance is rejected. The ONE in whom we are veritably united is Himself the great intolerance. He willeth to rule, to be victorious, to be - everything. He it is who disturbs every family gathering, every scheme for the reunion of Christendom, every human co-peration. And He disturbs, because He is the Peace that is above every estrangement and cleavage and faction.

Our generation has nobody home in the universe, nobody at all. Eventually, let us understand this: only a personal comforter can comfort man who is personal, and only one Comforter is great enough, the infinite-personal God who exists, that is the God of Judeo-Christian Scripture. Only He is the sufficient Comforter. Death in the City (Downers Grove, InterVarsity Press: 1969) 27