Christianity tells us that we are all sinners and doomed to Hell, unless we accept Jesus as our Savior. The reason we are doomed is that we are all sinners. The Apostle Paul says in Rom 5:12:
Wherefore, as by one man sin entered into the world, and death by sin; and so death passed upon all men, for that all have sinned:
The reason that we are all sinners is that we “inherit” the “Original Sin” of Adam. As sinners we deserve death. Only Jesus’ death could atone for Original Sin.
That puts Christians in an awkward position.
Christians have to hold that there really was an Adam and Eve and a talking Serpent in the Garden of Eden. They have to accept the creation story of Genesis. Most Christians have abandoned this position in favor of concepts like “divinely guided evolution”. A few Christians still argue in favor of creation a la Genesis but the arguments have been exposed over and over as baseless dogma and have rapidly lost traction among all but the most fundamentalist of Christians.
Or, Christians can accept evolution, even if they qualify it as divinely guided evolution. Then there was no Adam in a garden with Trees of Life and Knowledge. If there is no Adam, there is no Original Sin. There is only our nature (is it sinful?). And our nature is the product of evolution (is it divinely guided?). If there is no Original Sin, then why did Jesus die?