How did the Headmaster Change Roald Dahls views about important things?

The fact that the headmaster of his school could so savagely cane young boys

and at the same time, in his capacity as vicar, preached of the Lamb of God,

mercy and forgiveness was completely incomprehensible to young Roald.

It made him wonder whether the servants of God preached one thing

while practicing the other and caused him to have doubts about religion

and even about God.