[quote="DavidFilmer, post:2, topic:315342"]
Do not confuse Anti-Popes with Anti-Christs. Anti-Popes are not evil.
An anti-Pope is someone who claims to be validly elected as Pope, and usually believes his own claim. Anti-Popes are usually men of good will and intent who are answering the call to serve, usually unaware that the call is not legitimate. They are not acting out of evil intent (heck, one Anti-Pope is a Saint of the Church).
The process of electing Popes has changed over the years At times the process has not been very well defined, leading to confusion. At times, it has been very unclear whose claim is valid (and historians sometimes still argue about who was "really" the Pope in certain situations). The usual action is for both (or, in one situation, all three) claimants to renounce their claim so that an undisputed selection may be made (this is what happened 600 years ago, the last time a Pope resigned before Benedict).
All Anti-Popes (who have been recognized by the Church) are legitimate Bishops who exercise valid and licit Sacraments.
I know they weren't all evil. I'm sure some of them were holier men than the valid pope of the time.
You made a good point that they were still bishops so that takes care of the issue of the priests they ordained but what about the bishops? It is my understanding that only a Pope can appoint a bishop. Is that not the case?