If she is nervous about what people will think of her. then here is my suggestion:

Start out slow. Post some pics of her clothed, but still quite sexy (i.e: low cut blouse, tight jeans or even lingerie) and gradually work her way into posing nude.

Heck, I often find non-nude pics to be even more sexy because it leaves more to the inagination.

If she is worried about being seen by a mamber of her church:

1) Blur the faces.

2) When a deacon announces to the congregation that he saw your wife posing nude on the net, then loudly ask why the hell was he looking at a porn site? Or how exactly he can recognize your wife nekkid with her face blurred?

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Well sir that seems to be someone else's problem.