Well, it is not within the scope of this article to deal with the particular historical examples of slavery and racism. But what I do want to challenge is the presupposition that is behind the "wrong side of history" argument, that modern optimism is correct. Modern optimism believes that society is generally progressing positively and improving over time, including its views of morality. Yet, will history prove modern optimism to be true in practice? Even more importantly, as a Christian, what do the Scriptures say about this matter? Particularly with regard to morality, is society largely progressing in a positive way?
I would ask you to consider two passages that are particularly helpful in this regard. The first is Matthew 24. There, Jesus described the general troubles of a moral nature that the world would continue to face going forward. For example, he said that there would be "wars and rumors of wars", and that these are only "the beginning of the birth pains" (vs 6a, 8b). Jesus went on to describe the ways that Christians would even be immorally treated by people and many Christians would be hated (vss 9-10). And then notice what verse 12 says about that future: "lawlessness will be increased." This word for lawlessness refers to the sin and wickedness that will abound at that time. In other words, if anything, Jesus predicted that the future holds an increase in immorality, not a decrease.
I draw your attention as well to 2 Thessalonians 2. This is the chapter which describes that in the future there will come a "man of lawlessness," who is generally understood as a reference to the coming Antichrist. Among other things, it says this about this evil figure:
The coming of the lawless one is by the activity of Satan with all power and false signs and wonders, and with all wicked deception for those who are perishing, because they refused to love the truth and so be saved. Therefore God sends them a strong delusion, so that they may believe what is false, in order that all may be condemned who did not believe the truth but had pleasure in unrighteousness.
This man of lawlessness is someone who in the future will work to bring greater moral wickedness to this world.
Now it is acknowledged that Matthew 24 and 2 Thessalonians 2 don't say that there won't be any moral improvements made among society along the way. Certainly, some Christians have even argued from other prophecies of Scripture that there is yet to be some great moral progress in the future among society. Surely, interpreting prophecies of future events can be difficult, and we should have great humility when it comes to explaining prophecies that have yet to come to pass. However, even if we grant all those qualifications, the overall point still remains. Matthew 24 and 2 Thessalonians 2 rule out a simplistic and/or absolute optimism that would think too highly of human progress in terms of morality. Rather, Scripture would have us to recognize that Satan is continuing to be at work, looking for ways to increase immorality in this world.
Just because a future society looks back upon the moral judgments of Bible-believing Christians today and declares them to be wrong does not mean that this future society's judgment is correct. Rather, biblical prophecy calls us to be on guard against a growing immorality among society in the future. Consequently, if the future society, or even today's society, disagrees with biblical morality, that doesn't make society right. Actually, it only serves to highlight the wicked and perverse nature of that society which has denied biblical morality.
All this is to remind us that an even greater flaw behind the "wrong side of history" argument is that the ultimate judge of morality is not a later society sitting as judge of the history that was before it, but the eternal God who sits above all human history as the Sovereign King and Lord over all. It is this God who even foretold in ages past of a coming and growing lawlessness. Thus, when someone says that Christians are on the wrong side of history, these Christians may actually be on the right side of prophecy. In other words, though society may deem their moral convictions as immoral, prophecy says that you want to be those on the side of God's declaration of morality. A society's judgment in history might condemn your moral views, but the ultimate judgment is at the end of history where God will judge the living and the dead. It is to God that we must ultimately give account.
In light of this, we rejoice in the gospel that all the more continues to speak hope to our generation. If you are in this society where lawlessness seems to continue to grow, the gospel calls us to repent of our immorality, and to turn to Jesus Christ for forgiveness and grace. Christ died on the cross to atone for such sins. And so when we hear the words of prophecies, such as Matthew 24 and 2 Thessalonians 2, and see how they ring true in today's society, we are reminded of this need for the gospel. Every human is guilty of sin before God. In Christ, we can find divine pardon, so that on that future day of judgment we can be acquitted for Christ's sake, and because of his saving work on our behalf. May each one of us then repent of our sins and turn in faith to Jesus; become his disciple and follow him!