I consider traditional Christianity the most irrational and illogical than most religions, because it results in cultural meld of ancient mythical Babylonian/Canaanite/Ugarite Genesis, and Roman/Hellenist mythology to come up with the 'Fall,' 'Original Sin' as inherited sin, the necessity of the Noah Flood, and the purpose of Jesus as a sacrifice based on ancient mythical beliefs in the purpose of animal sacrifice, necessitates the sacrifice of Jesus to absolve the sins of humanity with this ultimate sacrifice to absolve the sins of humanity, though only those who sincerely believe. This results in a Resurrection Death cult, which results in contemporary Christianity.
This melding of ancient mythology with Roman/Hellenist mythology results in a non-rational and illogical religion, which results in an intense circular reasoning to justify its beliefs.