The Irony of Christianity
Christianity purports to be the religion that brings truth and liberation to all mankind as a free gift from God to give them freedom from death into life. Ironically, Paine argues that it does precisely the opposite; instead of freeing people, it forces them into slavery to the church and to arbitrary rules created by mere humans.
The Irony of Paine's Reputation
After writing Common Sense, Paine became famous in America for being a brilliant and inspirational thinker and rhetorician. In this volume, Paine intends to use his reputation to enact even more good in his readers' lives, giving himself a bit of a savior complex. Ironically, instead of improving his reputation, this book effectively destroyed it, giving Paine the common title of "heretic."
The Irony of the Age of Reason
Paine intended for this book to be primarily a defense of Deism, and an account of why he chooses to believe that over orthodox Christianity. Ironically, the book is now considered to be a harsh, intentional, malicious attack on the Bible and the Church, a position that Paine himself didn't necessarily want to be known for holding (hence his disclaimers at the beginning saying that everyone is entitled to his/her own beliefs).
The Irony of the Ten Commandments
The Ten Commandments are generally held to be some of the most foundational laws of the Christian religion, being given directly to Moses from God. Ironically, Paine goes straight for these; he argues that they really aren't that great, and that there's no proof that God wrote them, effectively alienating all of his Christian readers.
The Irony of the First Chapter
This book, which many consider to be a scathing attack on Christianity and organized religion as a whole, has a startling declaration at the beginning: "I believe in one God, and no more" (Chapter I). This declaration, after a couple sentences, is followed by a "but," which kicks off his harsh train of logic.