Do human have the right to change the definitions of sin?

Over history the clergy has called lots of things sinful: the railroad, cars, radio, TV, rock 'n roll, the ministers in my town all united one Sunday to preach against surfing, and the next Sunday to preach against skateboarding. I don't know what it is about the clergy, why they automatically condemn anything new and especially anything fun, more than that I don't understand why anybody pays any attention to them.