Paul describes those who talk the talk, but don’t walk the walk as arrogant. Their arrogance is rooted in their firmly held belief (and the lifestyle that flows out of it) that God’s approval is given to them because of their outward behaviour – regardless of the true condition of their heart. They are keeping up appearances, maintaining the external illusion of peace, harmony and unity whilst inside are enemies of God and the gospel of Jesus Christ.
… the kingdom of God does not consist in talk but in power ~ 1 Corinthians 4:20
You hypocrites! Well did Isaiah prophesy of you, when he said: “‘This people honors me with their lips, but their heart is far from me; in vain do they worship me, teaching as doctrines the commandments of men.’” ~ Matthew 15:7-9
This is the place to address those who, having nothing of Christ but the name and sign, would yet be called Christians. How dare they boast of this sacred name? … The Apostle denies that any man truly has learned Christ who has not learned to put off “the old man, which is corrupt according to the deceitful lusts, and put on Christ,” (Eph. 4:22). They are convicted, therefore, of falsely and unjustly pretending a knowledge of Christ, whatever be the volubility and eloquence with which they can talk of the Gospel. Doctrine is not an affair of the tongue, but of the life; is not apprehended by the intellect and memory merely, like other branches of learning; but is received only when it possesses the whole soul, and finds its seat and habitation in the inmost recesses of the heart. Let them, therefore, either cease to insult God, by boasting that they are what they are not, or let them show themselves not unworthy disciples of their divine Master. Calvin Institutes 3.6.4
The means to avoid this superficiality is provided in Jesus Christ through the gospel. As you deepen your delight in Christ, not in your performance and not in your ability to manage your external reputation, you move from “talk” to the “power of the kingdom of God.” Let him be your deepest delight and highest allegiance.