Pastor Armstrong taught that God hardened the hearts of Israel and turned their ears away so that they would not believe in Christ. Does that mean that God purposely prevented those people from believing in the Gospel?
The Bible teaches that the nation of Israel was “hardened” at Christ's appearing, which means God did not permit them to recognize their Messiah during His first coming. The Lord did this justly, because the Old Covenant required that Israel receive this penalty for their sin under the Law. (Please consult our Revelation study for more background on how the Old Covenant gave cause for Israel's hardening.)
We see the hardened of Israel mentioned clearly in Romans, beginning in chapter 10:
Paul says that not all Israel heeded the good news, just as Isaiah lamented in fortelling how no one in Israel would believe the report of the Messiah’s arrival. Faith comes by hearing, but the ability to hear (and believe) comes by the word of Christ. The Lord said through Isaiah that no one in Israel would believe the Gospel when Christ came the first time.
Paul knew we might try to "explain away" the fact of Israel's hardening. Perhaps we would assume that Israel’s failure to believe was merely because they didn’t hear the Gospel, but Paul disabuses us of that notion in v.18. Paul says the nation did, in fact, hear the Gospel as the word of God promised they would.
Still not willing to accept the truth of God's choice to harden Israel, perhaps we will say that Israel’s failure to believe was because the nation didn’t know Jesus was the Messiah, but in v.19 Paul counters that objection as well. Paul quotes from Deuteronomy, where Moses promised Israel that in a future day God would prevent them from receiving their Messiah because of their sins under the covenant. Instead, the Lord would permit Himself to be "found" by the Gentile nations instead, as a testimony against Israel of what they lost.
Finally, Paul tells us that Isaiah foretold boldly how only the Gentiles would find the Messiah, because Israel remained disobedient and obstinate. Based on Paul's teaching in Romans 10, our conclusion is unavoidable: Israel was hardened and prevented from receiving their Messiah so that the Gentiles could have opportunity to be saved.
Pauls reinforces this truth in chapter 11, when he teaches:
According to Paul, the Lord chose a remnant of Israel to believe the Gospel, because He has promised He will always maintain a believing remnant within Israel, but the "rest of Israel" were hardened by God. Nevertheless, God’s decision to harden the majority of Israel was not intended to destroy Israel.
In v.10 Paul quotes the Psalms where David declared that God would be just to darken Israel's eyes forever and bend their backs forever (i.e., to prevent them from receiving the Messiah forever) because of their unbelief and disobedience under the covenant, but God will not reject His people forever. Paul says in v.11 that their hardening was intended to bless Gentiles for a time, but eventually the Lord will return to Israel and bring the nation into faith so they may receive the glory He promised.
If you are struggling to understand the Bible's teaching concerning the sovereignty of God in these matters, we encourage you to read the article Wrestling With God on our website, which examines this issue in considerable detail.