“The wrath of God is revealed from heaven against every wickedness and unrighteousness of men, those in unrighteousness restraining the truth” (Romans 1:18).
Paul writes to and of Christians here; Christians who, because of their unrighteousness, are holding back the truth and who will face the wrath of God as a result. How do they do it? By talking about it but not living it; like the scribes and pharisees, “they say but do not do” as Jesus said (Matthew 23:3). The truth, you see, must be lived; if it is not alive in His people, then it is suppressed or restrained or held back; it cannot progress and do that for which it came. The unrighteous people of God claim to know the truth but their witness is not of life but of death. “You have a name that lives, but you are dead” was the rebuke to the Church at Sardis (Revelation 3:1). This is the unrighteousness of which Paul writes to the Romans.
This, too, Jesus warned against when telling the Jews that unless their righteousness exceeded that of the scribes and pharisees they would not enter the kingdom of heaven (Matthew 5:20). The righteousness of the scribes and pharisees was that they followed the letter of the Law, tithing dill and mint and cumin, but neglecting “justice, mercy and faithfulness” (Matthew 23:23); their righteousness was in appearances only, entirely external, whereas inwardly they were full of robbery and self-indulgence (Matthew 23:25); these are hypocrites, in the same way as false prophets, who come in sheep’s clothing but inwardly are like ravenous wolves (Matthew 7:15). It is their hypocrisy – unrighteousness – that restrains the truth and prevents the gospel truth from being released into the world.
Paul wrote that the Jews, failing to understand God’s righteousness, set up their own system of righteousness and so, were not under the righteousness of God. The same has happened in the era of the Church.
Against the example of religious hypocrisy that both Jesus and Paul admonished, we have the example of Jesus Himself – the king of righteousness. What did He do? “I am come to do thy will O God” (Hebrews 10:7). That was Jesus’ entire ministry; everything else that happened flowed from His obedience; redemption, justification, salvation, sanctification – all were made possible only because He obeyed the Father. The only thing that holds back the truth from flooding the world is the unrighteousness of those who claim to be His; this was true in Paul’s day; it was true of the Jews; and it is true of the Church.
Because of that, Jesus Himself has had to restrain, or hold back, the man of lawlessness from taking over the world until now (2 Thessalonians 2:6) because God’s people were restraining the truth in their own unrighteousness. But now we are in the time of the great apostasy, in which the restraint is released and the lawless one is revealed. In those days, God will send a deluding influence to the unrighteous Christians so that they will believe the lie; they received the truth but suppressed it in unrighteousness and did not love the truth so as to be saved (2 Thessalonians 2:10).