Some heresies are so ridiculous they just make you laugh

There are many things which deserve refutation in such a way as to have no gravity expended on them. Vain and silly topics are met with especial fitness by laughter. Even the truth may indulge in ridicule, because it is jubilant; it may play with its enemies, because it is fearless. Only we must take care that its laughter be not unseemly, and so itself be laughed at; but wherever its mirth is decent, there it is a duty to indulge it.

Tertullian
Against the Valentinians
Chapter VI

Denouncing prescribed prayer is a form of self exhaltation

The best thing, where it is possible, is to keep the patient from the serious intention of praying altogether. When the patient is an adult recently reconverted to the Enemy’s party, like your man, this is best done by encouraging him to remember, or to think he remembers, the parrot-like nature of his prayers in childhood. In reaction against that, he may be persuaded to aim at something entirely spontaneous, inward, informal, and unregularised; and what this will actually mean to a beginner will be an effort to produce in himself a vaguley devotional mood in which real concentration of will and intelligence have no part. One of their poets, Coleridge, has recorded that he did not pray “with moving lips and bended knees” but merely “composed his spirit to love” and indulged “a sense of supplication.” That is exactly the sort of prayer we want; and since it bears superficial resemblance to the prayer of silence as practised by those who are very far advanced in the Enemy’s service, clever and lazy patients can be taken in by it for quite a long time. At the very least, they can be persuaded that the bodily position makes no difference to their prayers; for they constantly forget, what you must always remember, that they are animals and that whatever their bodies do affects their souls. It is funny how mortals always picture us as putting things into their minds: in reality our best work is done by keeping things out.

C.S. Lewis
The Screwtape Letters

Virtue is a gift from God — man is not capable.

Consider how [Jesus Christ] teaches us to be humble, by making us see that our virtue does not depend on our work alone but on grace from on high. He commands each of the faithful who prays to do so universally, for the whole world. For he did not say “thy will be done in me or in us”, but “on earth”, the whole earth, so that error may be banished from it, truth take root in it, all vice be destroyed on it, virtue flourish on it, and earth no longer differ from heaven.

St. John Chrysostom
On the Lord’s Prayer