They always used Luke 19 which is the parable of the slaves who were put in charge of the masters belongings while he was away. The slave that made good use of the belongings /increased them, was praised, the one who didn't use them well/hid them away, was evil and cast off.
The idea was that the WT is using the Masters belongings wisely and if you don't support them, you are an evil slave deserving of death.
This assumes that the master is happy with how they are doing things. Hopefully the Master won't be annoyed by the lack of growth due to the slow and ineffective means they use to spread the word and by the literature containing incorrect dates and teachings that were spread through out the world that mislead many and turned many away from God altogether.