When a christian says "only God can judge me", it's usually an excuse to boldly partake in an activity that is contradictory to their faith and get away with it.

Notable examples,
1) Tonto Dike ,who has been declaring her spirituality and strong ties to christianity, wore an outfit that showed considerable portions of her breast and when confronted by people online if she was living according to her beliefs, she responded with the "only God can judge me" excuse and even threatened to wear bikini. Not only Tonto Dike but other christian and muslim ladies who love to wear skimpy clothes and do the so called worldly things their churches are against use this excuse very often.

Prostitutes who go to church ;Duse this excuse too. This is how you spot those who don't really believe in their holy book or religion but play the god card for social reasons. If a pastor raped any of these ladies or their daughters, they won't hesitate to call him names and judge him but yet they don't want people to do the same to them when they err. People who do this know that what they are doing is against what they profess to believe but they deliberately indulge. After all who no like better thing? make up and Luis vuitton is more fresher than the barren outlook of deeper life chicks. As an atheist, I am not saying that such dresses are sin but let's be sincere with ourselves.