2 John 10-11

10. If there come any unto you, and bring  not this doctrine, receive him not into your house, neither bid him God speed:

11. For he that biddeth him God speed is   partaker of his evil deeds.

This does not refer to the brethren in the local church, but to outsiders. 

This also makes it apparent that the truth is something that always must be at the forefront of our conversation and conduct. We are not to express or wish success to those who are in opposition to the truth. There is always an issue with heretics, whether they be brethren or outsiders; we cannot have normal relations with them.