If something, however, is to be described as merely mysterious, then mystery may not be at the very core of the phenomenon described.
Jimmy needs to get a flight to Detroit. He has the precise fare needed for a bus and a train to the airport. If Jimmy misses the last bus that would get him on time for the last train to the airport that would enable him to catch his flight to Detroit, then – according to this definition – it would be more fitting to describe his on-time arrival in Detroit as mysterious than A MYSTERY. It is not an unresolvable mystery to its very core that Jimmy made his flight. We can come up with alternative scenarios that meant that Jimmy got lucky.
What does it mean to say that God is one and tri-personal? It’s a mystery! I confess it now annoys me somewhat if, when a believer’s set of interpretations no longer holds together, they just play their joker card, and declare their belief to be a “mystery”. You can’t beat that card! Even the apostle Paul plays it that way, right? So some feel they can do this with authority because of how Paul speaks of mystery.
This way of understanding mystery is mistaken because mystery, exegetically, is about God’s inclusion of the gentiles, not about irreconcilable inconsistencies or contradicting points of view. According to the definition above, gentile inclusion is actually more mysterious than A MYSTERY because we do not see this inclusion as incomprehensible to its very core.