Since it's inception.
Not quite, but certainly since 300 AD and the Council of Nicea.
Triune God? Nope. There's just the Father and the Son. The Holy Spirit is the Father and often also the Son being subtle. Christ is less than God, as He repeatedly says in the Gospel. There is no triune godhead of three equal people. The triune godhead is a concession to Roman Paganism.
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