False teachers aren't Christians and 'the kingdom', here, isn't eternity in heaven.
False teachers are not Christians is a false statement. If you are a Calvinist, you think Arminians teach falsehoods, and vice versa.
I believe God chose to use born anew believers to be His ambassadors, carrying out the ministry of reconciliation. To the extent we fail to give the Lord our due diligence, we hinder His ministry, and we fail to "hasten the day" of His return, resulting in more people being consigned to Hades and Gehenna. Our rewards for being effective in the ministry results in us entering heaven abundantly, rather than as one escaping from a fire. False teachers hindered people seeking God according to
Matthew 23:13.
Is this a stupid or silly thread? Not actually. The OP authors point was that false teachers do not hinder the ministry of Christ, based on Calvinist dogma. That view is of course a false teaching which hinders the ministry of Christ. Our lack of diligence delays the second coming, and that increases the number of the lost consigned to Hades/Gehenna due to unbelief. (Matthew 24:14)