{Joint-heirs with Christ} (sunkl(8872)onomoi Christou). A late
rare double compound, in Philo, an Ephesian inscription of the
imperial period (Deissmann, _Light from the Ancient East_, p.
92), papyri of the Byzantine period. See  8:29  for this idea
expanded. Paul is fond of compounds of sun, three in this verse
(sunkl(8872)onomoi, sunpasch(936d)en, sundoxasth(936d)en). The last (first
aorist passive subjunctive of sundoxaz(935c) with hina (purpose),
late and rare, here only in N.T.