Now who exactly is Jesus addressing here in these passages? I’m not sure, but it could be either of three possible kinds of claims to Jewish identity, or some combination of them. First, there is the reprehensible but less fatal error of expecting that native Jewish identity and heritage gives the natural born Jew special covenant rights and favor over other gentile brethren. This is in manifest contradiction to the “mystery” that Paul proclaimed among the gentiles. (This propensity is currently making a come back).
However, it appears that the Lord is here denouncing something that is much more pernicious. All error is costly but not all error is fatal; this is fatal. It is more than pride of ethnic identity. It is the really Satanic presupposition that there is something good in man (Mt 19:17; Ro 7:18). It is the principle of all works religion that looks for something in the power of the creature on which it can base its hope of salvation or even a prideful distinction above others that permits judgment of others (Lk18:9; 1Cor 4:7). It is simply trust in the flesh. So the “Synagogue of Satan,” is, in one form or another, really just “the church of pride.” […]