Can you be saved if you do not believe in the Trinity?

Answer 1

The concept of the Holy Trinity came to the fore during the third century, with no actual biblical support*. Late in the century, Arius started a movement known as Arianism, opposed to belief in the Trinity. Arianism was opposed at the Council of Nicaea, but support continued strongly and it subsequently received support from several of the Christian emperors and came close to succeeding over 'Trinitarianism'. Had it done so, it would be Trinitarianism that would now be regarded as a heresy, not the opposite.

At the end of the fourth century, Emperor Theodosius came down on the side of Trinitarianism and declared it illegal not to believe in the Trinity. Thus, the success of the teaching of the Holy Trinity came from a political decision, and it would be rational to believe that Theodosius was wrong or ill-advised.

Footnote

A passage known as the 'Johannine Comma' (1 John 5:7) does refer indirectly to the concept of the Trinity, but was never in the early Greek manuscripts, only appearing in the Latin translation of the fifth century, after the Trinity doctrine had been accepted by the Council of Nicaea.