{A minister of the circumcision} (diakonon peritom(8873)).
Objective genitive, "a minister to the circumcision." Diakonon
is predicate accusative with gegen(8873)thai (perfect passive
infinitive of ginomai in indirect assertion after leg(935c), I
say) and in apposition with Christon, accusative of general
reference with the infinitive. See  Ga 4:4f . {That he might
confirm} (eis to bebai(9373)ai). Purpose clause with eis to and
the infinitive ebai(9373)ai (first aorist active of ebaio(935c), to
make stand). {The promises given unto the fathers} (	as
epaggelias t(936e) pater(936e)). No "given" in the Greek, just the
objective genitive, "the promises to the fathers." See  9:4,5 .