In October of 2020, Disney+ made headlines when it decided to place a warning ahead of two of Disney's classic movies, Peter Pan and Dumbo, warning audiences that these movies display stereotypes that "were wrong then and are wrong now". Though it is likely just more virtue signalling from Disney, I actually think this is an excellent thing. First, it's true that the movies do display problematic racial stereotypes, so it's actually a good thing to acknowledge, rather than just shy away from it, or even get rid of the movies. But it's also a good thing because it means Disney acknowledges that morality transcends humanity.
By placing this particular message ahead of their movies, Disney acknowledges that you can judge both historical morality, and other cultural norms. This eliminates almost all of atheism's alternative moral sources. Where does morality come from if not God? The law? No, because apartheid, slavery, even the Holocaust were legal, yet were wrong then and are wrong now. Cultural norms? No, because many cultures were very supportive of these racial stereotypes, yet these were wrong then and are wrong now. If you can say anything was wrong in the past, and is wrong now, you are saying morality transcends humanity.
This is why only Theists can claim morality is objective. If atheism is true, then morality is merely man against man. The one who is "right" is simply the one who is most capable of enforcing his will. But if that is the case, nothing is ever really right or wrong. It's just "done". And you might not like it, but "I like" is not the same as "I'm right". I like coffee, you might like tea. I don't like football, but you very well may.
So, morality is either objective, meaning it transcends humanity, or it is subjective, meaning all actions are morally equal. If atheism is true, morality is entirely subjective, but that means your opinion on any moral issue, even something as evil as gang rape, is worth as much as your opinion on whether pineapple goes on pizza. Now, if you want to claim that, go ahead, but only a sociopath could actually live that out. Anyone capable of remorse knows that there is such a thing as good and evil. But that leaves us with one conclusion: Some kind of personal god exists.
Unfortunately, this is the extent of the moral argument. It can only establish that any normal-minded human being instinctively understands that a god exists, and it's not them. But thankfully, the God that exists didn't just sit back and let us figure things out. Rather, He has been present with mankind since the beginning, revealing His will through prophets, and preserving that revelation in written form. He even verified these revelations through numerous miraculous acts, culminating with the death and resurrection of His Son.
Ultimately, God will judge everyone for the times they were right, and the times they were wrong, but the problem is, much like Disney, we all have a spotty past. But God's solution is a little more permanent than placing a few warnings on us. The punishment for sin is death. But in His love, this isn't what God wants for us, and so He gave us an exit strategy. When Jesus died, He was completely without sin, yet He was receiving a sinner's punishment. All sinners' punishments. Those who confess Him as Lord, and believe He rose from the dead, will not see the death they deserve, but instead receive the life He bought for us. This Gospel was right then, and it is right now.