R. v. Oickle, 2000 SCC 38 holds that police may properly offer spiritual inducements to suspects as part of interrogation.
As a result it is common for police to tell prisoners "the wages of sin is death" and to remind them of the saving "blood of out Lord and Saviour Christ Jesus".
56 A final threat or promise relevant to this appeal is the use of moral or spiritual inducements. These inducements will generally not produce an involuntary confession, for the very simple reason that the inducement offered is not in the control of the police officers. If a police officer says "If you don't confess, you'll spend the rest of your life in jail. Tell me what happened and I can get you a lighter sentence", then clearly there is a strong, and improper, inducement for the suspect to confess. The officer is offering a quid pro quo, and it raises the possibility that the suspect is confessing not because of any internal desire to confess, but merely in order to gain the benefit offered by the interrogator. By contrast, with most spiritual inducements the interrogator has no control over the suggested benefit. If a police officer convinces a suspect that he will feel better if he confesses, the officer has not offered anything. I therefore agree with Kaufman, supra, who summarized the jurisprudence as follows at p. 186:
We may therefore conclude that, as a general rule,confessions which result from spiritual exhortations or appeals to conscience and morality, are admissible in evidence, whether urged by a person in authority or by someone else. [Emphasis in original.]