1. Someone who believes in the doctrine of agathism which is, "all things tend towards ultimate good".
2. A person who believes that the world and things in general are heading for the better; therefore, in things that most people regard as evil or tragic including virulent diseases, calamitous earthquakes, or wars, the agathist can find some ultimate purpose for good.

The optimist sees the present as pretty much for the best; the agathist, less content with the present, thinks things are inevitably tending towards good despite the bad situations which precede the ultimate results.