"Give yourself a gift: the present moment. People out for posthumous fame forget that the Generations To Come will be the same annoying people they know now. And just as mortal. What does it matter to you if they say x about you, or think y?"
--Marcus Aurelius, Meditations, Book 8, no. 44 (see book image; emphasis added)
The Roman emperor gives shrewd advice. As St. Josemaría Escrivá said, our lives slip through our fingers like water. The emperor knew that truth also, a truth that led him to recommend living intensely and purposefully.
I do not adopt the extreme version (or caricature) of Stoicism that evil lacks reality (a tendency also found in St. Augustine's exploration of evil). Evil is quite real and quite destructive. Evil exists. Yes, metaphysically and philosophically, we can say that, compared to good, evil is empty and parasitic and thus, in a way, lacking in being and that this lack is its reality (compare this Augustine link and this Aquinas link). But, in ordinary language, the parasite causes real damage; and only something very real--not a mere lack or absence--can cause real damage.
What I do find persuasive in the Stoic outlook (a particular outlook also present in the Gospels and present in other religious traditions since the Holy Spirit reveals truth in some measure in varying degrees to all humans) is the emphasis on our freedom to defy the reality of evil without having to sugar coat it. I can choose to live the present moment intensely in defiance of evil. It is not a matter of denying the reality of evil or of deluding ourselves that evil acts are not harmful. It is a question of defying evil by living more intently, knowingly, and boldly. In other words, we would be wise to live intensely before the water of life completely slips through our fingers.