I telegraphed everything that could be said in the title if you already know the work of David Martyn Lloyd-Jones but since there's a chance you don't know his Studies in the Sermon on the Mount here goes.
Over the last few years I've been slowly going through the aforementioned studies (a very cool Christmas gift I got from my brother a few years ago). While the sermons were preached half a century ago they remain, of course, valuable. Since I don't take at all seriously James MacDonald's comment to Mark Dever that dead pastors' sermons should be taken out of circulation because the Spirit has stopped working through them I find it useful to review sermons by old dead pastors like Martyn Lloyd-Jones or John Donne (who, of course, was one of the most amazing poets in the history of the English language). As a matter of fact Donne's sermons on the Psalms proved valuable to me in helping me begin to reassess my problematic relationship to the literature in a church setting where the psalms are basically window dressing at most and were never taught from as part of teaching from the scriptures. One of the strongest reasons for my advocacy for reading the work of dead pastors is that your living pastor may stink at this or that aspect of preaching certain parts of the scriptures.
Appropos of contemporary Christians and blogging there is a widespread attitude (and I've seen it firsthand) not just among blogging Christians but Christians all sorts of places; this attitude is one which holds that "thou shall not kill" be kept in an entirely negative way. As Martyn Lloyd-Jones put it, it is the sentiment that so long as one does not actually commit murder one has fulfilled the purpose of the law. Of course this is far from true. Jesus goes on to say that though you have heard it said you must not murder if you are even angry with your brother you are in danger of judgment. If you call your brother a fool you are in danger of the fires of hell.
Particularly salient is the pastor's warning that we should not produce a kind of self-righteousness that reduces the law of God to something which we know we have already kept, or which we feel sure we are not likely to break. It is this warning, half a century before an age of theo-blogging, which remains endlessly pertinent to the whole enterprise of Christian blogging and, of course, life in general. This may well be the difference between a Christian blogger who does some limited good through blogging and the Christian blogger who merely blogs as a way to obtain a measure of glory for himself (usually) or herself (not uncommon). This is true in every age of Christians and of pastors. We must be vigilent against presenting the scriptures in such a way as to imagine that we ourselves have not broken the commands in them, let alone imply or state this to be the case to others in either our words or testimony.
But this far any Christian could point out, "This is simple enough. I don't wish harm on anyone." You do, you just have convinced yourself that you hold no contempt toward anyone at any point. I have struggled with it and struggle with it. This is no guarantee, of course, that you must have the same struggle I have. You probably have a very different struggle but there is no temptation except that which is common so though our temptations may differ in detail they do not differ in spiritual substance.
It is also important to note that Jesus said that if someone has something against you to leave your sacrifice at the altar and go be reconciled before offering your gift. It is this positive application Martyn Lloyd-Jones spends time discussing in his sermon that is most salient to blogging. We can be content to tear apart other Christians "in Christian love" through on-line statements and go without a pang of remorse to worship the Lord in whatever place and time we choose and believe that we are blameless. We may have said terrible things about a fellow believer and justify it on the basis that we are either speaking the truth in love or (depending on our social or political loyalties) speaking the truth to power when none of the above is really hapepning.
We may decide that what justifies this is simply deciding that whomever we ventilated via cyber-space is not really a brother or sister in Christ and that we are therefore discussing the person not as a Christian but as an apostate. And in some cases that may even be true but our blogging will very probably not win the apostate back anyway and we know it. We may simply decide someone is an apostate without sufficient grounds in their doctrine or ethics because we have other reasons to hold something against them.
Or we may not, it may be that a person has something against us that is because of a wrong we did that we do not consider to have been a wrong. Jesus doesn't frame his application of this command in terms of us exonerating ourselves because we think we've been true to all of the scriptures (because, really, how could we kid ourselves into thinking we haven't breached Christ's teaching at this point? (rhetorical question)).
Martyn Lloyd-Jones made an aside I want to allude to. He said that the Pharisees were very good at advocating ceremonial sacrifices to cover up moral failure. They went to the temple regularly and kept a steady schedule of times when they offered sacrifices. Yet they managed to do all this while holding people in contempt. They were condemning their neighbors in their hearts. The outrage of a theo-blogger or a Christian willing to go on-line to denigrate those who also identify themselves as Christians is a flamboyant, self-congratulatory violation of Jesus' expansion on "thou shall not kill" that is rationalized as a spiritual enterprise of the highest order. It is this reason, among others, that makes me cautious about many an on-line self-proclaimed prophet, whatever that person's understanding or application of "prophetic" may be.
As the pastor put it half a century ago, if you are not on speaking terms with another person or harboring resentments against another person then do not imagine the acts of worship you bring before the Lord are of any value. They may even, I dare say, stand as evidences against you before the Lord.
A particularly ironic application in the pastor's sermon is to refer to a man who decided that a partial fulfillment of the Lord's command was enough. Saul thought it good to merely kill some of the Amalekites rather than all of them. He saved some of the booty from battle on the pretext of making an offering to the Lord. He was met with Samuel's stern rebuke that obedience is better than sacrifice. Nevertheless, despite the irony, the point that merely partial obedience to the Lord's command is problematic. Most of us are not a messiah appointed to defend the Lord's people by destroying the enemies of ancient Israel. However, like Saul, we are often eager to take for ourselves certain privileges without the attendent responsibilities.
Martyn Lloyd-Jones goes on in his sermon to say something that I have not noticed too much in the Christian circles I've been in in the last decade, he says that he always felt sorry for Saul because he can relate to him. I have not usually heard a preacher, let alone a preacher from even a semi-Reformed tradition to say this. He says that we do not obey the Lord's command, we set limits on it, and then to cover up that we have set limits on what the Lord has truly commanded of us we go out and choose to make some great sacrifice to cover up our failings. We convince ourselves that the Lord will delight in the sacrifices we're making as compensation for our disobedience in holding brothers and sisters in contempt.
This, I propose, is in many cases the heart of a lot of theological blogging. Of course I don't say that it's all like that because it obviously isn't the case. Certainly I pray that's not why I do it even as I suspect it's often the reason why I do it. If you or I make gestures of confession or sacrifice so as to please the Lord or convince ourselves we are rightly worshipping the Lord but have let bitterness or resentment fester in our hearts our worship is a judgment against ourselves. But if we have wronged others and go to worship the Lord and think that the Lord will exonerate us because we know how sinful we are this allows us to abstract ourselves from our actual offenses against others.