The unbelievers; the unsaved; those without Christian faith; the lost and dead in sins.
(Does not refer to 'children' of a certain age; but rather, humanity in general.)

And you hath He quickened who were dead in trespasses and sins; Wherein in time past ye walked according to the course of this world, according to the prince of the power of the air, the spirit that now worketh in the children of disobedience: Among whom also we all had our conversation in times past in the lusts of our flesh, fulfilling the desires of the flesh and of the mind; and were by nature the children of wrath, even as others.
Ephesians 2:1-3