If you look also at other passage that refer to those who 'speak evil' of another you will see it bears out the same thing, such as with Peter and Jude:
Amen, those are very good examples that help demonstrate the motive of evil speaking. Thanks Allan!
Which brings us back to the Lord's sermon on the mount; the law was concerned mainly with outward actions and behaviours, but now in Christ, we are held to a higher standard. Our motives and intentions for our actions will be judged in addition to the actions themselves.
Which is why we should be prudent before and while judging a fellow Christian, to examine ourselves first, to make sure that our intentions are pure, and that we are not guilty of the same things. Confrontation should never be to tear down, to humiliate, to punish, to make them "feel bad", to teach them a lesson, et cetera. It should only be done with the intent to restore, to edify, to rebuild, to help them become a better and stronger Christian.
Galatians 5
25 If we live in the Spirit, let us also walk in the Spirit.
26 Let us not be desirous of vain glory, provoking one another, envying one another.
Galatians 6
1Brethren, if a man be overtaken in a fault, ye which are spiritual, restore such an one in the spirit of meekness; considering thyself, lest thou also be tempted.
2 Bear ye one another's burdens, and so fulfil the law of Christ.
3 For if a man think himself to be something, when he is nothing, he deceiveth himself.