Theosis (Greek: θέωσις), or deification (deification may also refer to apotheosis, lit. "making divine"), is a transformative process whose aim is likeness to or union with God, as taught by the Eastern Orthodox Church and the Byzantine Catholic Churches. As a process of transformation, theosis is brought about by the effects of catharsis (purification of mind and body) and theoria ('illumination' with the 'vision' of God). According to Eastern Christian teachings, theosis is very much the purpose of human life. It is considered achievable only through synergy (or cooperation) of human activity and God's uncreated energies (or operations).