I recently asked several fellow Witnesses what the hallmark of a true Christian was?
To save embarassing any of them who may say the wrong thing, I quickly said, "Knocking on doors to offer strangers the Watchtower & Awake? No, Jesus told us at John 13:35, that it would be if we had love amongst ourselves!"
One individual was quite insistent that it was the preaching work - so I politely repeated what Jesus had very clearly stated.
I then mentioned that it would be good if we could spend a fraction of our witnessing time, to actually visit our existing brothers!