What shocks Mr. Walter and the other members in the church about Tom having the highest tickets ?

Walters never expected Tom to EVER have enough tickets for a Bible. Other members of the church are shocked by the fact that Tom was using tickets they provided.

This was a thunderbolt out of a clear sky. Walters was not expecting an application from this source for the next ten years. But there was no getting around it—here were the certified checks, and they were good for their face. Tom was therefore elevated to a place with the Judge and the other elect, and the great news was announced from headquarters.

The boys were all eaten up with envy—but those that suffered the bitterest pangs were those who perceived too late that they themselves had contributed to this hated splendor by trading tickets to Tom for the wealth he had amassed in selling whitewashing privileges. These despised themselves, as being the dupes of a wily fraud, a guileful snake in the grass.