As important as The Church/Body of Christ is, it seems puzzling to me why Jesus left talking about “this mystery” almost entirely up to Paul, with him having to convince the other apostles of this teaching given him by The Lord Jesus Himself.
I believe Jesus made no direct mention of the Gentile Church (and especially the rapture/resurrection) out of consideration for Israel. From my studies, I’ve come to the conclusion that His offer of the Kingdom to Israel remained open until the ascension 40 days after his resurrection. He had fulfilled the promised sign of the Prophet Jonah (Matt. 12:38-40) and knew they wouldn’t accept it, but He waited for them anyway. Therefore, any clear mention of His plans for the Church during His earthly ministry would have been premature because it would have taken the focus off His promise to Israel.
Although the Old Testament reveals that it was always God’s plan to bring His salvation to the Gentiles (Isaiah 49:5-6), this could have been accomplished through Israel. Therefore the Kingdom was theirs for the taking, and had they accepted the Lord’s death as the final sacrifice for their sins there would have been no Church. Daniel’s 70th Week would have come, Israel’s enemies would have been destroyed, and the Kingdom Age would have begun.