What are the signs of a true believer?

They can cast out devils, speak in tongues, handle poisonous snakes, drink poisonous fluids without harm, and heal the sick by touching them.

And these signs shall follow them that believe -- in my name shall they cast out devils; they shall speak with new tongues; they shall take up serpents; and if they drink any deadly thing it shall not hurt them; they shall lay hands on the sick and they shall recover; Mormon 9:24