Aww, the Catholic League was just "joking." It does make me wonder whether the program was meant to be tongue-in-cheek from the start, or they just freaked out when a bunch of atheists volunteered. The fact that they took down their contact page seems to me to suggest the latter, but I seriously doubt they'll ever own up to it.
For the record, if there are any Christians (or religious people of any denomination) who are still interested in attempting to persuade an atheist that he or she is wrong about your god, my offer still stands. It seems unlikely, now, that the Catholic League is likely to put me through to someone, but I also posted my position in the comments thread on Greta Christina's original post on the topic, and emailed it to my local American Atheists affiliate.
So, fingers crossed. (No, not like that.)