What is the description of evidence and how is it established?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.

It is not permissible to declare someone as a non-Muslim or an innovator, whether an individual or group, unless the conditions of declaring someone a non-Muslim are met and there are no impediments.

Among these conditions:

1-     Establishing the evidence against him/them.

2-     The person not being ignorant and the impossibility of misinterpretation of texts.

The evidence is established by informing the ignorant person, and arguing the scholar, based on evidence and proof until the matter becomes crystal clear. If after all this, a person does not embrace Islam or does not stop his innovation, then there is no harm in calling him a non-Muslim or an innovator, if the conditions are met and there are no impediments which prevent declaring him as such. 

Allaah Knows best.