One common argument among atheists is that since evolution is a fact, there was no Adam to be responsible for original sin, and so Christ as a savior paying the sin debt is unnecessary.  This is based on the commonplace conservative penal substitution interpretation of the cross (as opposed to the moral influence theory), and is probably not historically accurate.

The idea of original sin isn’t in the Hebrew Scriptures, so we should be wary about finding it in the New Testament, since what clearly is in the Hebrew Scriptures is my responsibility for my own sin.  For Paul, the theme of the Adam story is how death came about placing man in a condition of sinfulness, which was beginning to be treated with the cross of Christ.  To be “in Adam” doesn’t emphasize being a literal descendant from Adam any more than Paul means “in Christ” implies we are literal descendants of Christ.  Rather, two kinds of humanity are being contrasted.  Dr. Christopher R. Smith argues

• Personally, however, I do not believe it is necessary to conclude from Paul’s arguments in 1 Corinthians (“as in Adam all die, so in Christ will all be made alive”) and Romans (“as through the disobedience of the one man the many were made sinners, so also through the obedience of the one man the many will be made righteous”) that the human race must have begun with a single, directly created individual named Adam.  And I believe I can say this on biblical grounds…It could well be argued that in 1 Corinthians and Romans, Paul is indeed envisioning Adam as a specific historical individual.  I believe that to understand the Bible’s meaning, we must carefully consider the immediate context first, and the larger canonical context only second.  But once we do place Paul’s comments about Adam and Christ within the framework of the entire Scriptures, I think we can justifiably understand the phrase “in Adam” to mean “member of the human race,” rather than limiting it to “descendant of this named individual.”  This is because the Hebrew word ‘Adam is used in an intriguing variety of ways in the book of Genesis, where it figures prominently in the opening narratives.  Sometimes it seems indeed to be the name of a single historical individual, as in this statement:  “When Adam had lived 130 years, he had a son in his own likeness, in his own image; and he named him Seth.”  But in other contexts (in fact, in the immediately preceding statement), the term refers more generally to humanity as created in the image of God.  Note how ‘Adam in this case takes both singular and plural pronouns, and embraces both male and female: “When God created ‘Adam, he made him in the likeness of God. Male and female he created them, and he blessed them and named them ‘Adam when they were created.”  Elsewhere in the book of Genesis, the term ‘Adam refers to the growing human race.  The statement translated in the NIV as “when human beings began to increase in number on the earth” is more literally in Hebrew “when the ‘Adam began to be numerous upon the face of the ground.”  So in light of the use of the term in the book of Genesis, I understand ‘Adam to mean essentially the human race, at whatever stage of its expansion may be in view.  By putting Paul’s comments in 1 Corinthians and Romans in conversation with the Genesis narratives, I understand his phrase “in Adam” to mean being a member of the human race…In the same way, as members of the human race, we are alienated from God because of the disobedience of our race.  Mercifully, I am reconciled to God through the work of Jesus Christ, the Son of God, if I join through faith in his covenant relationship with the Father.  But even then it is not considered that I have personally lived a sinless life and died on a cross for the sins of the world.  Jesus alone did those things.  Rather, I am included in the rights, privileges, and responsibilities that come with my covenant identification with Jesus, which include both forgiveness of sin and reconciliation to God, and a duty to offer the same kind of loving obedience that Jesus did.  So, in short, I do not believe that Paul’s arguments in 1 Corinthians and Romans require Adam to have been a historical individual.  We need to make our mind up about that question on different grounds, and I think it’s fair and reasonable to bring scientific accounts of human origins into conversation with the Bible as we do so.  As I’ve tried to explain here, I think the language of the Bible can accommodate this.  See https://goodquestionblog.com/2015/03/20/does-pauls-argument-that-we-are-in-Adam-prove-that-Adam-was-a-real-historical-individual/

Similarly, Dr. James McGrath argues:

• I was asked a question on Facebook, and thought I would share the answer I gave. Here’s the question:

• I was hoping for a little clarification on how one might reconcile a non literal first Adam with Paul’s gospel…In Paul’s mind Christ is the “second Adam,” having succeeded where the “first Adam” failed. According to Paul, it is precisely because of the failure of the first that the second was required.  Can anyone point me in the right direction to help me resolve these complex theological challenges?

• Here is what I wrote in response:

• This is a great question. What I would note is that, if Adam in Genesis 2-3 is simply a symbolic depiction of what is typical of humanity in general, then the comparison still works just fine: Jesus succeeded where human beings in general failed, not just where one failed.  The contrast seems to me to be between two ways of being human, and just as being in Christ is not about being descended from Jesus, there is no obvious reason why being descended from Adam is crucial to the comparison.  I would also note that Paul plays fast and loose with the details in Genesis in order to make the contrast he does. If he were a literalist, he would have said “just as through two human beings sin entered the world…” The story as read literally is about a man and a woman who eat what they are not supposed to. Clearly Paul’s aim is not to stick to the details of Genesis as literal fact not to be tampered with, but to say something about Jesus. https://www.patheos.com/blogs/religionprof/2015/07/no-adam-no-christ.html

Further, McGrath says

• And once that cord is cut, the role of Adam as paradigmatic human can be brought to the fore, as a story not about a historical ancestor, but about everyone.  Yesterday in a Facebook group I participate in, it was pointed out that, unless one has the Genesis 2 creation account in mind, when one reads Genesis 1, one will not necessarily get the impression that God, creating Adam (which means humankind) male and female, made only one of each. https://www.patheos.com/blogs/religionprof/2015/03/review-of-the-lost-world-of-adam-and-eve.html

Paul is interested in 1 Corinthians in persuading those who don’t believe in the resurrection of the dead that the dead are indeed raised and Christ is the proof.  In fact, the cross is of no effect if Christ is not raised.  He says

• 12 Now if Christ is proclaimed as raised from the dead, how can some of you say there is no resurrection of the dead? 13 If there is no resurrection of the dead, then Christ has not been raised, 14 and if Christ has not been raised, then our proclamation is in vain and your faith is in vain. 15 We are even found to be misrepresenting God, because we testified of God that he raised Christ—whom he did not raise if it is true that the dead are not raised. 16 For if the dead are not raised, then Christ has not been raised. 17 If Christ has not been raised, your faith is futile, and you are still in your sins. 18 Then those also who have died in Christ have perished. 19 If for this life only we have hoped in Christ, we are of all people most to be pitied. (1 Cor 15:12-19)

The Adam story discusses how death came into the world and created fertile soil for sin, because if we are just going to die anyway, we will do whatever we feel like:

Isaiah 22:13

“Let us eat and drink,

    for tomorrow we die.”

Paul thus says

1 Corinthians 15:32

32 If I fought with wild animals at Ephesus with a merely human perspective, what would I have gained by it? If the dead are not raised,

“Let us eat and drink,

    for tomorrow we die.”

It is death and a lack of belief in the afterlife which is the true condition that results in man being sinful  that Paul is countering, because if the dead are not raised then everything is inherently meaningless and so you might as well do whatever you want:

Ecclesiastes 9

• 9 All this I laid to heart, examining it all, how the righteous and the wise and their deeds are in the hand of God; whether it is love or hate one does not know. Everything that confronts them 2 is vanity,[a] since the same fate comes to all, to the righteous and the wicked, to the good and the evil,[b] to the clean and the unclean, to those who sacrifice and those who do not sacrifice. As are the good, so are the sinners; those who swear are like those who shun an oath. 3 This is an evil in all that happens under the sun, that the same fate comes to everyone. Moreover, the hearts of humans are full of evil; madness is in their hearts while they live, and after that they go to the dead. 4 But whoever is joined with all the living has hope, for a living dog is better than a dead lion. 5 The living know that they will die, but the dead know nothing; they have no more reward, and even the memory of them is lost. 6 Their love and their hate and their envy have already perished; never again will they have any share in all that happens under the sun.

The story of the resurrected Christ had a powerful effect, because it spoke to the tragic nature of human existence.  Cleary, a penal substitution cross is not in play here because, as I quoted from Paul above, the argument is if Christ is not raised, we are still in our sin. A moral influence cross can be seen, not as Jesus dying instead of me (what did I ever do to deserve capital punishment ?!), but rather the soldier in Luke looking at Jesus dying on the cross and saying “Truly this was an innocent man.” Not God satisfying his divine wrath against sin, but “Father forgive them.”

In truth, though, the brevity of human life is also responsible for the beauty of it, because imagine the horrific tedium of an eternity in heaven doing nothing but praising and worshipping Jesus …