Dear Orion,
If anyone is experiencing anti-social behavior, it makes much more sense to seek professional help to sway that wrong behavior than simply maiming yourself. That does nothing for the person. The wrong has to be addressed before the person is freed from whatever their "sin" is.
Matthew 18 is a beautiful picture of God's concern for the humble and the lost.
This is not something that Jesus would actually have us do, but rather the extent in which He would have us desire go in order to keep from offending our brothers, or the lost. He did as much, by laying His own life down on our behalf...though we were guilty of offense, He did not offend us, but saved us with love. God cares so much for the wayward child, or the young in the faith, that He goes to great lengths to find them and teach them. The angels watch His face, and they know of how He suffers when we, believers, offend the lost and one another...especially our younger brothers and sisters. I would rather do those things that Christ mentioned than cause my children, or others, to end up in Hell because of my offense...my sin. I think of this sometimes when my children bicker with one another, or hurt one another's feelings. It grieves me when they hurt one another, or cause each other to sin...especially when they have missed out on wonderful opportunities to be examples of love, obedience, and Truth. God expects us all to shine, especially toward one another, with Truthful Love.
Concerning the help for social behaviors, the change in a person after they have been regenerated is such a change that someone would be willing to do almost anything to please God. To keep themselves from evil doing, and to avoid other things for the sake of offense. This passage is a picture of that attitude. I think that professional help these days mainly consists of psychology, and this is a teaching of man...of the deceiver. It is moslty unScriptural. In most instances, especially in things like marriage counseling, this route does more harm than good for believers. It is self focused, and Jesus' words are meant to teach us a great measure of self-denial for the love of others.
I hope that you can see the great love in this chapter.
As far as David's Word, and God's...yes, it's both. God is artful, and He created David with a heart that was very similar to His own. He also, through inspiration (Which most artists will tell you is real), gave David many words...words of prophecy, love, observations of His ways, etc. David's 'conversations' with God teach us, and inspire us, and help us to know Him better. They are also a model of prayers, and songs, that we ourselves may articulate when in trial. It's not the Bible that is worshipped, it's the One who inspired holy men to write it.
I think one is guilty of worshipping Scripture when they walk by the letter, and not by the Spirit...and expect others too as well. It's a distortion, and then making an idol of that distortion. Scripture, for the believer, is a love letter...not a yoke to be bound to or to bind others with. For example, if you have a love, and that love writes you beautiful words of love, of directions about a meeting, of requests on what you can do for him/her, then won't you read it carefully...follow it carefully...to please your love...especially if you love merits all that behavior? This is why we study, why we delight in the Law, and the knowledge of God. I know that my explanation may be simple, but I hope that it still encourages you. The Lord bless you.