From Hypocrites Deficient in the Duty of Prayer by Jonathan Edwards:
We are often taught, that the seeming goodness and piety of hypocrites is not of a lasting and persevering nature. It is so with respect to their practice of the duty of prayer in particular, and especially of secret prayer. They can omit this duty, and their omission of it not be taken notice of by others, who know what profession they have made. So that a regard to their own reputation doth not oblige them still to practice it. If others saw how they neglect it, it would exceedingly shock their charity towards them. But their neglect doth not fall under their observation; at least not under the observation of many. Therefore they may omit this duty, and still have the credit of being converted persons.
Men of this character can come to a neglect of secret prayer by degrees without very much shocking their peace. For though indeed for a converted person to live in a great measure without secret prayer, is very wide of the notion they once had of a true convert; yet they find means by degrees to alter their notions, and to bring their principles to suit with their inclinations; and at length they come to that, in their notions of things, that a man may be a convert, and yet live very much in neglect of this duty. In time, they can bring all things to suit well together, an hope of heaven, and an indulgence of sloth in gratifying carnal appetites, and living in a great measure a prayerless life. They cannot indeed suddenly make these things agree; it must be a work of time; and length of time will effect it. By degrees they find out ways to guard and defend their consciences against those powerful enemies; so that those enemies, and a quiet, secure conscience, can at length dwell pretty well together.