What is Salafism as a methodology, and is it permissible to affiliate oneself with it and to condemn those who do not?

Salafism is the adherence to the methodology of the Prophet, peace be upon him, and his companions. As for adopting it as a partisan methodology that misguides opponents or divides Muslims, this contradicts true Salafism. The Salaf used to call for agreement and unity around the Sunnah of the Messenger, peace be upon him, and they did not misguide those who differed with them in practical matters. Rather, they were tolerant of jurisprudential and doctrinal differences where ijtihad (independent reasoning) is permissible, without declaring others disbelievers or misguided. True Salafism is following the methodology of theaf in belief, speech, action, unity, and mercy.