I have to say, I laughed out loud at the word "reasonable" present in your question. Reasonable? Of course it's not reasonable! Reason and faith are often at exact odds with each other. The belief in life after death has to do with faith, not reason. Ironically, the century involved matters not. It is the reasonable who are happily atheist, ... it is the faithful who believe in life after death. This is the same whether you are talking about the first century or the twenty-first.
In my opinion, this is the reason why the American "Founding Fathers" struggled so very much with Christianity even as they were incorporating it into the Constitution of the United States. If you read Ben Frankilin's Autobiography, you will see this struggle. Christianity? Deism? Atheism? Ah, the conundrum.
I would argue that it is no more or less reasonable to believe in life after death today than it ever was. Of course, this is simply a matter of opinion.
Of course, we have made so many scientific breakthroughs to this point in history that we know much more than we used to about various natural phenomena. We no longer have to believe in supernatural origins for things like the Bubonic Plague, for example. But science cannot shed any light on what happens after death, if anything. A person's soul (if it exists) is not something that can be seen by science. Science cannot tell what happens to that soul after we die.
With all our scientific achievements, we know no more than people 1,000 years ago about what happens after death. Therefore, it is no more or less reasonable to believe in an afterlife today.