Not a trick question: 27. And there is more (that I learnt from Bart Ehrman): this is trinitarian, since the NT is about the Christian God, and therefore specifically about the Trinity. And what is 27? 3 to the 3rd power (3 x 3 x 3).
(Also there are 3 letters in New and 9 in Testament so 3×9 = 27)
(Also there are 3 letters in New and 9 in Testament so 3×9 = 27)