Shaykhul Islaam Ahmad ibn Taymeeyah 728AH (May Allah have mercy on him) said,

فكل من أعرض عن الطريقة السلفية النبوية الشرعية الالهية فانه لا بد أن يضل و يتناقض و يبقى في الجهل المركب

“So everyone who turns away from the divine legislative prophetic path (of the salaf), then it is a must for him to be misguided and to contradict (himself), and he remains in (a state of) compound ignorance.”

Taken from: Darul Ta’aarud 3/370