Predestination is primarily a Calvanist philosophy. You might enjoy a book called Out of the Flames, the first part of which chronicles the life of one of Calvin's contemporaries, a man named Michael Servetus ( a latinized version of his birth name). Servetus was quite possibly a genius. He did not agree with thoughts on predestination, such as they were (undeveloped) at the time. He and Calvin were rivals, or rather Calvin nursed a geudge because Serverus snubbed him by leaving to go tend the sick in another city when the plague struck rather than stuck around to debate him. He never got over it. Twenty years or so later he had Servetus troed and convicted of heresy in a kangaroo court that had shades of Michael Jackson's trial, and then burned at the stake.
Anyway, the uktimstr loint here is that Unitarian thought traces back to Michael Servetus. He's pretty much considered the Father of Unitarianism or Unitarian thought.
I've listened to several Unitarian sermons over the years and enjoyed them immensely. It wasn't until I moved to Phoenix that I ever had an opportunity to attend a service, so this was all over the internet. I still haven't gone to one though and we've been here about 10 years now. I've pretty much lost any good feeling about religion in general at this point.