Researchers consider Zoroastrianism to be the first successful monotheistic religion with a rejection of monasticism, or devoting one's life purely to the pursuit of spiritual works. It is one of the earliest examples of radical Dualism, where two equal forces are opposed to one another in a constant struggle.
Zoroastrianism is one of the oldest religions still in practice today. While Akhenaten in Egypt is described as being the first to convert a polytheistic system of belief to a monotheistic system, the traditional beliefs were mostly restored upon his death. The exact date of the birth of Zarathushtra, the progenitor of Zoroastrianism, is not exactly known, but likely predates Akhenaten, at around 1500 B.C.
Zoroastrians traditionally do not proselytize, or try to convert those of other religions, and this was even once considered a crime punishable by expulsion. They believe that each faith ultimately leads to God, all religions are equal, and that conversion is ultimately futile. Zoroastrians also put a focus on free will, with no compulsion to prayer and no requirements to do so. The religion has a focus on the elements of fire and water, both being noted in their scripture as being life-sustaining forces, with fire being a medium for spiritual insight and wisdom, and water being the source of that wisdom.