The word "apostate" is a label used by orthodoxy to malign heterodoxy.
The basic idea expressed by the word "apostate" is "someone who has abandoned his ideals." A deserter. Someone who is no longer cheerfully attending all the meetings, perhaps?
Next up the scale are the "infidels," or "unfaithful" ones. We might imagine that at some point an apostate might perform some forbidden act, like joining a political orrganization just so they could use their library, or joining the YMCA just so they could use the pool.
Worse than an apostate would be a heretic, for a heretic holds unorthodox opinions. A heretic has ideas. I suppose that technically, "evil slaves" would be heretics. If you don't keep up to date with the color and intensity of god's ever-changing light, you might be a heretic!
None of these labels leave much room for the effects of education and growth, do they?
Human history is a progression of ideas. Was Martin Luther an apostate, infidel or heretic when he nailed his message to the church door? Was Charles Taze Russell an apostate, heretic or infidel when he began publishing Zion's Watchtower? It all depends on who is answering the question.
The Watchtower Bible & Tract Society can call me anything they want. They have no power in my life, nor do they have any metaphysical power. Their power is all about money and lawyers, manipulation, guilt and lies.