Did Jehovah not tell people who to worship until 1954?

The power in the Watchtower often tells the followers that God has given them 'New Light. This is the way they get around changing their doctrine now and again. What God told them one year is no longer true this year apparently because of this 'New Light'. This is why many leave the J.Ws. after being members for decades. They eventually see that they have been taught things which are untrue.