"God's in His Heaven, All's Right With the World" is the last line from the
poem Pippa's Song (from
Pippa's Passes) which was written by
Robert Browning.
Pippa's Song and this line in particular caused Browning many problems because a lot of people just heard the line and didn't consider it within the context it was written.
Pippa, in the
poem, knew that everything wasn't all right with the world, she was an exploited
orphan girl who had to work long hours in terrible conditions. When you look at the whole poem, it should be taken to mean that despite all the evil and injustice in the world, we can still believe that
God is there, and thus all is right with the
world.
As to whether I agree with Browning is another story...
It is also interesting to note that this line is used as part of
NERV's Mark in
Neon Genesis Evangelion.