Who wrote God grant you the serenity to accept the things you cannot change the courage to change the things you can and wisdom to know the difference?

Answer:

Reinhold Niebuhr

Addendum: Niebuhr's, The Serenity Prayer (1934) reads:

"God, give us grace to accept with serenity
the things that cannot be changed,
Courage to change the things
which should be changed,
and the Wisdom to distinguish
the one from the other.

"Living one day at a time,
Enjoying one moment at a time,
Accepting hardship as a pathway to peace,
Taking, as Jesus did,
This sinful world as it is,
Not as I would have it,
Trusting that You will make all things right,
If I surrender to Your will,
So that I may be reasonably happy in this life,
And supremely happy with You forever in the next."

The Web page of "The Voice of Love" reports the following:

"Reinhold Niebuhr ... discusses the Serenity Prayer and how it came to be in his book, The Essential Reinhold Niebuhr: Selected Essays and Addresses:

'... The embarrassment, particularly, was occasioned by the incessant correspondence about a prayer I had composed years before, which the old Federal Council of Churches had used and which later was printed on small cards to give to soldiers. Subsequently Alcoholics Anonymous adopted it as its official prayer. The [AA] prayer reads: "God, give us grace to accept with serenity the things that cannot be changed, courage to change the things that should be changed, and the wisdom to distinguish the one from the other." ...'