I don't think they do. If they did they would not feel the need for things like Judicial Committees. They'd leave it to God who supposedly can see all to judge peoples heart condition.
I remember a young sister who left home and went to live with her boyfriend. The parents were 'adamant' witnesses but did not want their daughter judging by the JC so they advised her to refuse to see the elders. Now since the elders are 'the stars' of the congregation appointed by God's holy spirit, you'd supposedly be worried about disobeying these men and fear God's retribution.
The parents said, that since the Elder's daughters, several of them, had not been disfellowshiped for living with their boyfriends, and even having children, then their daughter would 'not be getting into trouble either'.
Now putting aside the fact that I both agree with and am impressed with this couple for the support of their daughter, doesn't it make you wonder if JWs actually believe that there is an Almighty God Jehovah watching them and keeping his congregation clean with a 'fine' body of elders.
So, do JWs believe in God and fear him, or do they just worship and fear the WTBTS, which is what I think.