Final answer:
Many Greeks turned to Mystery cults, Stoicism, or Epicureanism because the Greek religion lacked a clear doctrine of an afterlife, where Stoicism and Epicureanism offered philosophical frameworks for achieving happiness in life.
Step-by-step explanation:
As the Greek religion did not provide a clear doctrine of an afterlife, many people began to follow Mystery cults as a means to achieve happiness and hope for a life beyond. Hellenistic philosophies like Stoicism and Epicureanism also emerged. Stoics, such as those who followed Zeno's teachings, believed the universe was governed by divine reason or Logos, which determined the fate of all people. The aim was to find happiness by accepting fate and coping with life's hardships without succumbing to extreme emotions. In contrast, Epicureans, followers of Epicurus, sought pleasure as the key to happiness, avoiding both physical and mental pain, not through indulgence but through enjoying life's simple pleasures.