It's not your place to call them to repentance. I would suspect that if you believe they have made false accusations against you, that you have every right to push the abuse button. If you feel they have made false allegations against your church, then your duty is to prove them wrong using facts and persuasive arguments.
Yes it is. False accusations in nearly every post, day and night, are wrong, Marlowe. People need to be willing to tell the truth, to learn kindness, meekness, and humility, charity and benevolence, and it needs to show in their posts.