Morgan means business here, as he gives a stark warning to an unseen character, telling them the life they're choosing leads to death and giving them the chance to leave and never come back. There's a slight moment that leads you to believe it's Rick he's talking to, but that never really seems likely. Just afterwards we see him using his staff in an assault on (who appears to be) Father Gabriel, which should mean that he is finally getting his comeuppance and hopefully leaving the group of survivors before too long, either by getting killed or being forced out.