Romans 11:25 For I would not, brethren, that ye should be ignorant of this mystery, lest ye should be wise in your own conceits; that blindness in part is happened to Israel, until the fulness of the Gentiles be come in. [kjv]
ου γαρ θελω υμας αγνοειν αδελφοι το μυστηρ ιον τουτο ινα μη ητε εν εαυτοις φρονιμοι οτι πωρωσις απο μερους τω ισραηλ γεγονεν αχρι ου το πληρωμα των εθνων εισελθη [gnt]
Paul was usually writing to a Greek audience who would have the background of the meaning of the word "
mystery" as connected with a somewhat secret society and of initiation into that group to get that knowledge and benefits.
Part of the "
mystery" involves the "
blindness" of the Jews, until the time of the Gentiles is complete. That is, until the time of the Kingdom of Heaven, or age of the church, is complete.
This "
blindness" appears to be stated by Jesus in Luke 13:34-35.