Anyone who does some reading about Stoicism has encountered books in which it is compared, unfavorably, to Christianity. These books seem to have been written, at the latest, in the 19th and early 20th centuries. More recent books about Stoicism don't make the comparison, and I wonder whether there simply is no longer an interest in doing so. Sometimes, the comparisons that were made seem to be in earnest, and even thoughtful. Sometimes they seem quite partisan, and far less than impartial. They all seem to have certain claims in common, however.
I've sometimes wondered whether Christian thinkers have resented Christianity's great debt to pagan philosophy. Christianity hasn't benefited merely from Stoic influence, of course. It incorporated the thoughts and works of Plato and Aristotle as well; Christian mystics and ascetics spoke and conducted themselves much as the ancient Cynics did. The influence of the school of Epicurus is not as evident, as may be expected.
The early Christian Fathers didn't share in such resentment, though, nor does it seem to have been prevalent in medieval times, or during the the Renaissance when Aristotle was "the Master of All who Know" and he and other pagan thinkers spent their time in Hell in its relatively comfortable first level, according to Dante. Certain of the Fathers, at least, spoke of Plato and others as having approached the truth, a remarkable concession from an otherwise highly intolerant crew. Seneca was considered a kind of Christian, and Marcus Aurelius was said to have regretted or to even have been ignorant of the persecution which took place during his reign. It was in a sense assumed that people who wrote and thought and acted so wisely, as these figures did, could not really have been all that unchristian; indeed, must have been proto or quasi-Christians.
Perhaps this kind of hat-tipping to the pagan thinkers began to disappear as it became clear that such fabrications as the correspondence said to have taken place between Seneca and St. Paul was established as being forged, and other myths such as Plato's friendship with Moses were found to be contrived. I suppose it may have been easier to acknowledge the extent to which Christianity borrowed from the ancients when it was at least arguable that Christianity or "proper" Judaism influenced the works of the old philosophers in some respect.
It seems clear, though, that the New Testament doesn't indicate that Jesus and his disciples discussed or were much concerned with the fundamentals of pagan philosophy which became the fundamentals of Christian theology. So some justification was required when the equivalent of Plato's forms and Aristotle's First Mover and natural law and universal law began to appear in defenses and explanations of the Christian religion. Perhaps the acknowledgement simply became more grudging or reluctant.
We see Stoicism sometimes described as the noblest of the moral codes pagan antiquity managed to formulate. But there is always something wrong with it according to these writers, something which, they maintain, caused it to dissipate though it was at one time the preferred philosophy and even religion of the thoughtful Roman upper and mid-to-upper classes. It was, of course, Christianity that satisfied the need Stoicism could not. Stoicism's subsequent revivals over the centuries in, for example, Justus Lipsius are acknowledged by these writers, but they seem to consider these events as similar to fits or fads.
As might be expected, Stoicism's failure is ascribed to the fact that it's tenets are too stern, cold, abstract, unrealistic. It's claimed that the Stoic view of the emotions and passions was too negative. Most of all, it seems, it's claimed that Stoicism failed to acknowledge or recognize love--which is to say Christian Love. And it's claimed the Stoic view of God was materialistic and distant, despite the efforts of Seneca and Epictetus to portray God as more the personal God of Christianity (more personal, at least, when that characteristic fits the apologist's purpose; the God of the famous proofs is notably vague and abstract).
What Christian Love is supposed to be is an interesting question. The Gospels were written in Greek by men who could not have known Jesus personally. Was the "love" referred to in the Gospels or St. Paul the kind of "love" we may read about in the works of the pagan philosophers? Was the "love" presumably referred to by Jesus the same, or something different?
There are quotes from the early Stoics which seem to support the claims the writers make. However, more recent thinkers have found the Stoic view of the emotions to be far more sophisticated than previously believed, and the therapeutic effect of Stoic practice to be far more effective than previously believed.
It's possible Christianity may be waning now, or that the personal God posited by it an other established religions may be considered less and less credible the more we know of the universe. Stoicism is not so limited, however, though there also seems to be nothing prohibiting the Stoic from suspecting that God is, in a sense, concerned with human beings and "personal" in that sense. Perhaps it is this flexibility that is one of the reasons it keeps appearing. It's by no means defunct, and I suspect it never will be.