2 Not unmindful of this sin of wilfulness, the Apostle, writing to Timothy, after many injunctions to bear witness to the faith and to preach the word, adds, For the time will come when they will not endure sound doctrine, but having itching ears will heap up teachers to themselves after their own lusts, and will turn away their ears from the truth, and turn aside unto fables. For when their unhallowed zeal shall drive them beyond the endurance of sound doctrine, they will heap up teachers for their lusts, that is, construct schemes of doctrine to suit their own desires, not wishing to be taught, but getting together teachers who will tell them what they wish: that the crowd of teachers whom they have ferreted out and gathered together, may satisfy them with the doctrines of their own tumultuous desires.
And if these madmen in their godless folly do not know with what spirit they reject the sound, and yearn after the corrupt doctrine, let them hear the words of the same Apostle to the same Timothy, But the Spirit says expressly that in the last days some shall away from the faith, giving heed to seducing spirits, and doctrines of devils through the hypocrisy of lying talk. What advancement of doctrine is it to discover what one fancies, and not what one ought to learn?
Or what piety in doctrine is it not to desire what one ought to learn, but to heap up doctrine after our desires? But this is what the promptings of seducing spirits supply. They confirm the falsehoods of pretended godliness, for a canting hypocrisy always succeeds to defection from the faith: so that at least in word the reverence is retained, which the conscience has lost. Even that pretended piety they make impious by all manner of lies, violating by schemes of false doctrine the sacredness of the faith: for they pile up doctrines to suit their desires, and not according to the faith of the Gospel.
They delight, with an uncontrollable pleasure, to have their itching ears tickled by the novelty of their favourite preaching; they estrange themselves utterly from the hearing of the truth, and surrender themselves entirely to fables: so that their incapacity for either speaking or understanding the truth invests their discourse with what is, to them, a semblance of truth.
Source: On the Trinity (New Advent)