Final answer:
John likely needs a written confession as a formal record of acknowledgment or for legal purposes, with the exact reason depending on his specific circumstances and the context of the situation.
Step-by-step explanation:
The character John presumably needs a written confession for reasons of validation, legality, or personal closure. A written confession serves as a tangible record that can be referenced and authenticated. The context in which this need arises could vary, ranging from a legal proceeding, where it would serve as evidence, to a more emotional context, where it might represent the acknowledgement of wrongdoing and the beginning of reconciliation. Without more specific information related to John's situation, one can only speculate on the exact purpose of the confession.