Perry, is the Watchtower a Christian religion in your view or a cult following the rules of men? If a cult, does that mean they are doomed because they had the Bible to read but failed to show the qualities Jesus Christ said his followers would display?
BSB,
Not a cult for following the "rules of men", but a cult because of the reason why they do it. It is OK to follow the rules of men if you want to, for your own various resaons to suit you. That is biblical Christian Freedom. It is NOT OK to follow rules of men for Salvation from judgment. That is idolatry. Your reasons are everything to God and reveal the nature or quality of your faith.
However, on your second question: Jehovah's Witnesses aren't doomed because they failed to show Christ's qualities. They are doomed because they fail to have faith in Christ Alone; which failure nullifies the contractural obligation of God to pay the sin debt on your behalf through the blood of his only Son. Personal efforts at righteousness are offensive to God, and only serve to pile up more debt for a person on Judgment Day.
Romans 4
4 Now to him that worketh is the reward not reckoned of grace, but of debt.
5 But to him that worketh not, but believeth on him that justifieth the ungodly, his faith is counted for righteousness.
6 Even as David also describeth the blessedness of the man, unto whom God imputeth righteousness without works,
7 Saying, Blessed are they whose iniquities are forgiven, and whose sins are covered.
8 Blessed is the man to whom the Lord will not impute sin.