One of the greatest, I'll bet, is apostasy.
But what about others? What is someone has committed adultery? Or even murder? If someone murdered someone twenty years ago, could they receive baptism? And what if someone committed adultery with a high church official or his wife? If an official heard someone admit to a heinous crime committed years ago (and which has no statute of limitations), would he be required to report it to law enforcement?
What if someone committed apostasy, started a website for former members and then wanted to suddenly return?
If I recall correctly, the wages of sin is death, and those who fight Jehovah won't be tossed into a fiery pit, but simply uncreated and become nothing. Is that correct? And if so, what of Jesus' saying that it would be better is such people had never been born or had the proverbial millstone tied around their neck and thrown into the sea?
What of those who lived and died without hearing the gospel? Or what of aborted infants, or infants who died at birth? Are these saved through the grace of Christ? And if apostasy is considered a great sin, is it the "unforgiveable" sin mentioned in scripture? Are people ever declared to be guilty of such in this world? If so, by whom?
Since I've never been to a Kingdom Hall meeting, is the Lord's Supper observed there? I understand this sacrament is limited only to the 144,000 heavenly class, and that this class has pretty much been exhausted. How is one supposed to know if one is of the heavenly or earthly class? It seems I was told years ago that John the Baptist was not deemed to be of the heavenly class because Jesus said, "He who is least in the Kingdom of Heaven is greater than he." Most Christians believe this was a statement of Jesus saying that he, Jesus, who because of taking the sins of the world upon himself, thus had the least claim on the Kingdom of Heaven; yet he was greater than John the Baptist. Jesus always equated the least with the greatest, and I can't believe the JW theologians missed what I see as an obvious interpretation. But then, I guess I'm just not spirit led.