Not a problem, I typed a 3 instead of a 5, it happens.
We'll have to agree to disagree on that quote. While I do concur that we are to strive for agreement (I Peter 3:8 and Philippians 2:2) - and we ultimately will as true believers - we're still going to get some things wrong. I think Christianity, even amongst the elect, is characterized by strife even over the simplest of terms or doctrines. I think some of this comes about as a result of passages like those in II John (which are the result of an earnest desire to be correct), but I think you can distinguish those by how the person handles their discussion be it on a forum or face-to-face. We're not Christ and we don't have the benefit of Father's omniscience so we don't know if that mind might change a day, week, or years later to the truth. There's only one unpardonable sin, and not understanding a certain passage of the Bible is not it.
Christ teaches us on many levels, and I don't think there is a difference here. Yes there is the apparent level of the believer and nonbeliever and then the believer and the deceived, but there's also a good bit of evidence for the believer and the believer. The whole chapter of Luke 12 seems to me to be addressing some of our common human conditions and problems. We have fear, we get anxious (worry), we tend to quarrel even when we agree, and we tend to become passionate about things that don't really matter (the clouds and the winds) that we don't see the forest for the trees. It is a lot of pride as Ronnie says, but it's predicted that love will grow cold because that pride is ultimately a desire to edify one's own self.
We like to be religious and we like to be holy, but sometimes we don't want to do the real legwork to get there. If Christians would approach everything with humility, things might be different. You're not out there to win every fight or to come up with the cleverest comeback. We're here to say what needs to be said. I think it's rich when these people say they're persecuted because their insulted. We don't have much comprehension of what it means to be martyred or what the prophets and apostles endured. Instead, take a step back, make your case (argue the doctrine not the person) and move on when what needed to be said was said.
All of this doesn't mean that we have to be politically correct or drop our defenses. We wear the gospel armor and should always be on guard. However, it's military strategy that you don't always respond with the heaviest force. (IE: You don't nuke the other nation when some infantry exchange fire or mutual allies don't go to war over a small trade dispute.) That's an example of hyperbole I know, but you get the point.
That doesn't mean there aren't different types of love to applied from one situation to the next, but love will always build in the end just as our Savior did.