I think if Christian posters figured out a central truth of forum posting (and being a Christian), then this place would go back to being friendlier. What most folks do not seem to get (I see this play out over and over) is that running down your opponent, insulting, and otherwise belittling/attacking them is not the Christian way. It never makes your point and often does the opposite. I agree with the notion of the persecution complex because you see it on forums. Most often it comes from the ones who do persecuting themselves when they don't agree. The reality is that its generally very hypocritical.
I have found the following reasons for people to be hostile when posting.
1. They feel they have been personally hurt or attacked.
2. They feel that they are fighting for God.
3. Luke 18 describes a relationship between self-righteousness and contempt for others.
4. Failure to distinguish the difference between what is right and what is true.
The worst examples of behavior I have found to be in the so-called Christian "science" forums. I generally do not even read the posts in these forums anymore due to the extreme examples of bullying and intimidation.
Being "right" is generally being conformed to some standard. In Christians circles this is often the doctrinal positions of denominations. This often becomes semantical gymnastics like the definition of the word "repent".
One of the "works of the flesh" in Galatians is HERISIS. We get the word heresy from it, but at the time it meant divisions. In a way it is at the core of denominationalism. Often a person or a group will define something and declare it as sacrosanct. Thus anything contrary must be fought.
For example, there are many theories on the exact process of salvation (from baptisms through faith, and onto works). Many people argue over the process and some people are left uncertain of their own salvation. The Bible describes both uncertainty and certainty such that one might conclude that Christian maturity (Christ-likeness) creates a closeness to our Savior from whom we can draw our certainty. This would seem to be more certain than denominational assurances often predicated on specific word definitions.
Another problem is that people think it is their responsibility to prevent error. Paul tells Timothy to correct error, but nowhere is anyone instructed to prevent error. The attempt at prevention only leads to organizational control systems hardly discernible from socialist and communist control systems.
We need to relax. No one is going to hell because of what we fail to do. We need to trust that God will accomplish His purposes with or without us. We also need to be able to handle not understanding everything. There is little to be gained from arguing if hell is eternal or not if we do not fully understand what eternal means. The Greek word Aion usually means "age". However, if we do not understand if eternity is the end of time or time unending, we may not want to get into arguments beyond what we can know or understand.
Complicating things even further are the many people who view Christianity from a "warm puppy" perspective. It is possible to get "chastised" by someone because they felt bad about something that was posted. For example, a person may post a challenge to abandon worldliness and someone else may feel that the poster is lacking in "grace" or "Christian love" by being judgmental or unloving.
The key to cutting through all of the hostility is to elevate truth. If I make a suggestion, ask a question, or offer advice it should come from a heart that seeks the truth in love. If I get rebuked, flamed, or told off, I need to reconsider if my words were in truth and love. If they were, then I should consider that whoever responded is not discerning and is unable to respond to truth. There is nothing that can be done to convince such a person. The best that can be done is to ignore them.
The best example is Jesus. There are times when He is silent and times when He is not silent. One example are the scribes in the temple who challenged Him by asking what His authority was. Because of their position, they had a right to ask Jesus. However, Jesus didn't answer, but gave them a test. He asked them if the baptism of John was of heaven or of men. They responded they didn't know. They in fact had abrogated their authority by having no interest in the truth. If someone makes an attacking comment and demonstrates no interest in truth, there is no obligation to respond.
It has been my experience that frustration is a result of a conflict between what I expect and what actually happens. I usually need to review a frustrating experience and determine what led me to expect something that I shouldn't have. If I present what I feel to be truth, and it is not well received, I do not feel that I am obligated to go any further.