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.
Israel’s blindness:
Paul says that the reason that Israel does not accept Christ as the Messiah is that there is blindness in part in their seeing, reading and understanding of Scripture and of Jesus. He tells us that it is only a part (portion, measure) of blindness but not a type that prevents them from ever coming to the truth. In 2 Cor 3 Paul speaks of the clarity of his presentation of the gospel and associates this with the partial blindness of Israel when these same truths are presented to them. In verses 13-16 he explains the truth of what has happened with the incident when Moses talked with God and then with the people and had to place a vail upon his face when speaking to the people because he shone with the glory of God (Ex 34:31-35). Paul says that this vail remains upon the hearts of Israel until they turn to Christ in faith through the working of the Holy Spirit thru the preaching of the word (1 Cor 1:21).
The vail on Gentiles:
Paul tells us that the unbelieving Gentiles are darkened in their understanding (Eph 4:18) because of the blindness of their hearts. This blindness comes in part because the devil is the prince of the darkness (Eph 6:12) against whom we wrestle in this warfare. All unsaved are in darkness because the devil has blinded their minds (2 Cor 4:1-4). Paul speaks of the light and dark that is in this world and the numerous things that can cause and keep people in darkness (Rom 13:12; 2 Cor 6:14; Eph 5:8, 11) until they turn to the Lord thru the light of the gospel as the Holy Spirit illuminates truth to them and awakes their conscience. The masses are held in darkness by the devil and it is our call to send the light and then allow God’s Spirit to awaken. Then after He has awakened we are to disciple. teach and mentor them into the kingdom and greater truth and light.
Purposeful darkness:
There are many who purposely embrace the darkness because they refuser to accept the truth and willingly accept untruth as truth (2 Pet 3:5) and accept lies so they may continue in their sin (Rom 1:21) and live as they please professing themselves to be wiser than God. Prior to Paul’s exposition of the truth of Israel’s blindness, he quoted from Psa 69:23) in which David prays that God would cause darkness to come upon them because of their sin and refusal to accept and seek God and His ways. Jesus said if we know the truth it shall set us free. Paul also said that in the last stages God would cause may people to believe the lie of the anti-Christ because they refused to believe His truth (2 Thes 2:11-12).
Present day blindness:
Many today are in darkness because of the false teachers, preachers and Christians who only spread darkness and not truth. They may be like the two disciples on the road to Emmaus who eyes were holden (held back, retained) because of their unbelief and prejudice. Through faithful preaching and teaching and presentation of truth some, perhaps many, will turn to the Lord but far too many will willingly refuse to grasp the truth and will be eternally lost.