Homoiousion (Greek homoiousios, "of like substance") was the fourth-century semi-Arian compromise term proposed in the years after Nicaea — affirming that the Son is of like substance with the Father rather than the same substance. The single Greek letter iota separated it from the Nicene homoousion ("of the same substance"). Athanasius and the orthodox party rightly rejected the compromise: like is not same, and a Christ who is only similar to God cannot save. The struggle is the perpetual lesson of doctrinal precision — small words carry whole gospels, and the church that yields a single iota of Christ’s deity has yielded everything. Nicene Christology stands or falls on that letter.