Saint Augustine is well known for (primarily) three things:  His intimate Confessions, his majestic City Of God, and his heated debate with Pelagius.  It is in this debate that Augustine's positions on Predestination and Perseverence of the Saints (eternal security) finds its final and strongest articulation (1000 years before Calvin!).

Pelagius, thanks largely to the tireless efforts of Augustine, was universally recognized as a heretic.  There were some at this time, however, who disagreed with both Pelagius and Augustine, and sought more of a middle road.  These people came to be called "semi-Pelagian" and eventually "Arminian" (after the position's strongest and most infamous Protestant proponent, Jakob Arminius). 

Today there are no confessing Pelagians (although many evangelical Christians today have Pelagian tendencies they are largely unaware of).  Thus the debate that goes on today within evangelicalism is between Calvinists and Arminians.  Since I am a Calvinist, I obviously have plenty of concerns and disagreements with Arminian theology.  However, I have noticed a strong tendency in many Calvinists today to simply think of their semi-Pelagian opponents as full Pelagians.  Or, if they acknowledge the difference, they still tend to treat semi-Pelagianism as if it represents no improvement on Pelagianism at all.   The implication of this sort of thinking is clear: Pelagianism is a universally recognized heresy, liable to lead its adherents straight to damnation.  If semi-Pelagianism is no different...

But Calvinists today would do well to remember that Saint Augustine himself faced semi-Pelagian critics in his own day, and he always treated them as erring brothers, not heretics.  The Augustine-Pelagius debate may have meant eternal life or death, but the Augustine-semi-Pelagian debate was an intramural one. 

It is possible to hold the truths of Scripture in the highest regard without sacrificing charity.  Indeed, it is possible to fight hard for those truths without sacrificing the Apostle's command, "love one another."