You bring up good points. We do need to judge them by their fruit and sheep are never wolves and wolves will never become sheep, sheep are sheep and wolves are wolves. John 10:14-15 "I am the good shepherd. I know my own and my own know me,15 just as the Father knows me and I know the Father; and I lay down my life for the sheep." Before Christ died He seen His people as sheep, not goat that would become sheep, no they are sheep and sheep are His.
Here's where I draw the line, if someone continually makes immature posts, against God's word. I question their heart, it's one thing to be uninformed, it is a totally different thing to make remarks about God's word that border on blasphemy, there is no reason for that. It reveals the heart, the truth of God's word is not a joke or a common thing, like His name and He places His word above His name. Name, can be authority and/or nature and He has placed His word above that, making it very important to Him.
Psalm 138:2 I will worship toward Your holy temple, and praise Your name for Your lovingkindness and Your truth; for You have magnified Your word above all Your name.
Be careful of mocking God's truths that you don't understand. How can someone mock God's word or truths and be His? A true seeker is not going to mock something they does not understand, because it's God's word and if we don't call them on it, how are they to know that they could very well be blaspheming, if their reaction is more mocking, we know that they are not of the Lord.
A born again seeker of truth does not mock God's revealed truths, if they don't understand them they simply ask more question to help them understand or they will go to the word and let God reveal it to them.
To the Law, it is a guide to the foolish, babes, blind and those in darkness, because it's the embodiment of knowledge and truth. When we teach them we teach ourselves as well, if we brake them we are a hypocrite. Romans 2:17-24 “But if you call yourself a Jew and rely on the law and boast in God18 and know his will and approve what is excellent, because you are instructed from the law;19 and if you are sure that you yourself are a guide to the blind, a light to those who are in darkness,20 an instructor of the foolish, a teacher of children, having in the law the embodiment of knowledge and truth—21 you then who teach others, do you not teach yourself? While you preach against stealing, do you steal?22 You who say that one must not commit adultery, do you commit adultery? You who abhor idols, do you rob temples?23 You who boast in the law dishonor God by breaking the law.24 For, as it is written, “The name of God is blasphemed among the Gentiles because of you”.”
The Law brings the knowledge of sin. Romans 3:19-20 “Now we know that whatever the law says it speaks to those who are under the law, so that every mouth may be stopped, and the whole world may be held accountable to God.20 For by works of the law no human being will be justified in his sight, since through the law comes knowledge of sin.”