Cheever and Parris each accuse Proctor of not being a good Christian in Act 3. Parris does so as to discredit Proctor's defense for his wife Elizabeth in this act, but Cheever feels he has no choice but to be honest with the court.
Cheever tells the court that he watched Proctor, in anger, tear up the warrant for Elizabeth's arrest. Of course, cooperating with the law would have made Proctor look like a much better Christian especially if the court suspects his wife of being in alliance with the devil.
When Danforth asks Proctor if he considers himself to be a good Christian, Parris pipes up that Proctor does not attend church on Sundays except for maybe once a month. As if this is not damning enough, Cheever adds that he sees Proctor plowing the fields on Sundays - a serious offense. Sunday is a day of rest and is meant to be a day of worship ONLY.