Complex sentence: Zoroaster proclaimed that there is only one God, the singularly creative and sustaining force of the Universe, and that that human beings are given a right of choice, and because of cause and effect are also responsible for the consequences of their choices.
Split into simpler sentences: Zoroaster proclaimed that there is only one God, the singularly creative and sustaining force of the Universe. He also stated that human beings are given a right of choice, and because of cause and effect are also responsible for the consequences of their choices.