Neostoicism (not to be confused with modern Stoicism, which is a 21st century movement) was a syncretic philosophical movement, founded by Flemish humanist Justus Lipsius, that attempted to combine the beliefs of Stoicism and Christianity.
Neostoicism was founded by Flemish humanist Justus Lipsius (1547 – 1606), who in 1584 presented its rules, expounded in his book De constantia (On Constancy), as a dialogue between Lipsius and his friend Charles de Langhe. In the dialogue, Lipsius and de Langhe explore aspects of contemporary political predicaments, by reference to the classical Greek and pagan Stoicism, in particular as found in the Latin writings of Seneca. He further developed Neostoicism in his treatises Manuductionis ad stoicam philosophiam (Introduction to the Stoic Philosophy) and Physiologia stoicorum (Physics of the Stoics), both published in 1604.
Neostoicism is a practical philosophy which holds that the basic rule of good life is that the human should not yield to the passions, but submit to God. Neostoicism recognizes four passions: greed, joy, fear and sorrow. Although the human has the free will, everything that happens (even if it is wrong because of the human) is under control of God and finally it tends to the good. The human who complies with this rule is free, because he is not overcome by the instincts. He is also calm, because all the material pleasures and sufferings are irrelevant for him. Finally, he is really, spiritually happy, because he lives close to God.