In reply to Jackie walker.

I myself did not fully understand this thesis yesterday, when I searched the Internet for an explanation of it. I found that I was not the only person who was confused by it. I also found that Luther explained it in a letter that he wrote to an Augustinian prior in 1516. Here is his explanation:

You are seeking and craving for peace, but in the wrong order. For you are seeking it as the world giveth, not as Christ giveth. Know you not that God is "wonderful among His saints," for this reason, that He establishes His peace in the midst of no peace, that is, of all temptations and afflictions. It is said "Thou shalt dwell in the midst of thine enemies." The man who possesses peace is not the man whom no one disturbs—that is the peace of the world; he is the man whom all men and all things disturb, but who bears all patiently, and with joy. You are saying with Israel, "Peace, peace," and there is no peace. Learn to say rather with Christ: "The Cross, the Cross," and there is no Cross. For the Cross at once ceases to be the Cross as soon as you have joyfully exclaimed, in the language of the hymn,

Blessed Cross, above all other,
One and only noble tree.

It is posted here: http://www.ccel.org/ccel/luther/first_prin.iii.i.html