Shaikh Salih al-Fawzaan was asked: "Is [entry into] Paradise and Hellfire dependent upon the correctness of one's manhaj (methodology)?"

His reply: "Yes. When a person's manhaj is correct he will be in Paradise. So if he is upon the manhaj of the Messenger (sallallaahu alaihi wasallam) and the manhaj of the Salaf us-Saalih, he will become one of the inhabitants of Paradise by Allaah's permission. And when he travels upon the manhaj of the misguided strayers, he is threatened with the Hellfire."

(Al-Ajwibah al-Mufidah p.77)