God’s ways are often hard to comprehend (33-36). Paul calls the ones in these verses a mystery. All the interweaving complexities of everything and everyone is hard to comprehend. They are humanly impossible to mentally grasp let alone understand how God is organizing all of them for good.
Paul is talking here about how God is working with and in Israel and the Gentiles for mutual benefit. Much concentration is needed here to understand what Paul is saying God is doing.
God’s desire is that “all Israel will be saved” and “so that he may have mercy on them all.” Accepting that is enough for me today.