Paul tells Titus that those who try to push their religious opinions onto others as valid doctrines do so out of impure motives. He says they do it for “dishonest gain.” This phrase usually refers to monetary profit, but it’s also used to refer to prideful gratification. When Paul tells his readers to watch out for the wolves in sheep’s clothing who will distract you from the Gospel truths the Apostles passed on to the church he warns them about false motives. Wolves scatter the flocks. 
They steal, kill, and destroy. Wolves do not feed the flock, they do not care for the flock and they do not comfort and birth the little lambs. They simply fleece and kill and eat.
David’s sins were sins of an impure heart. When he confesses and pleads with God for forgiveness he also asks God to “create in me a pure heart.” A pure heart revolves around pure motives. It is what is meant by the passages that call us to love God with all our heart. Deeds are observed by man and are accepted, but God always looks at the heart. We are more concerned with conduct than motives. But to God actions are secondary to motives. The holiest service, the greatest sacrifice is deemed unacceptable to God when impure motives are the source. Proverbs 21:27 says, “The sacrifice of the wicked is an abomination; how much more when he brings it with evil intent.”
Now, don’t misunderstand. We all have impure motives to some extent. David, the man after God’s heart was not perfect, and neither am I and neither are you. The false teachers are not perfect either and to give any human the authority in our lives that belongs only to God, is to demean the person and work of Jesus Christ. John Stott said it well; “Only one act of pure love, unsullied by any taint of ulterior motive, has ever been performed in the history of the world, namely the self-giving of God in Christ on the cross for undeserving sinners.” All men are sinners and the only hope for sinners is the sinless one, the Lord Jesus Christ.
Chuck
“And there is salvation in no one else, for there is no other name under heaven given among men by which we must be saved.” Acts 4:17