In The Name of Allaah, The Most Merciful, The Bestower of Mercy.

Al-Allaamah Rabee Bin Haadi [may Allaah preserve him] said that Shaikhul Islaam Ibn Taymiyyah [may Allaah have mercy upon him] said: The people in their pursuit of knowledge and religion have two innovated paths and a path legislated in the Sharee’ah. The path of the Islamic legislation is to look at that which the Messenger brought, utilise it as evidence and act upon that which it necessitates. Therefore, there has to be knowledge based on that which he [i.e. the Prophet] came with and adherence to it, and only one of them is not enough. This path is built upon the sound intellectual proofs and the sound proofs that are based on absolute certainty (in agreement with the unadulterated divine revelation), because indeed the Messenger [peace and blessings of Allaah be upon him] clarified the sound intellectual proofs whose limits are determined by the divine texts and the Messengers clarified the sound rational proofs which people are in need of, just as Allaah put forth in the Qur’an every kind of similitude. This is the straight path which Allaah commanded His servants to ask Him to guide them to.

As for the two innovated paths, one of them is the path of the people of innovated theological speech and indeed there is much falsehood in this. Many of its people are negligent in that which Allaah and His Messenger commanded, so they remain upon corruption in knowledge and deeds. These people stray towards false Judaism.
The second one is the path of those people who adopt ways of strengthening the soul- the people of the Soofi paths and innovated acts of worship. These ones stray towards false Christianity, because they say that if a person purifies his soul based on the manner in which they have stated, then the sciences of the religion will come to him in abundance without learning. The acts of worship of many amongst these people are innovated; rather they are in opposition to that which the Messenger [peace and blessings of Allaah be upon him] came with and thus they remain upon corruption in their deeds and corruption due to deficiency in knowledge, because they do not know what the Messenger came with. These people often malign one another and every group speaks ill against the other, whilst each of them claims to be following the Messenger; but what the Messenger came with is neither in agreement with what these ones say nor what those ones say. Allaah said:

مَا كَانَ إِبۡرَٲهِيمُ يَہُودِيًّ۬ا وَلَا نَصۡرَانِيًّ۬ا وَلَـٰكِن كَانَ حَنِيفً۬ا مُّسۡلِمً۬ا وَمَا كَانَ مِنَ ٱلۡمُشۡرِكِينَ

Ibrahim (Abraham) was neither a Jew nor a Christian, but he was a true Muslim Hanifa (Islamic Monotheism – to worship none but Allah Alone) and he was not one who associated partners to Allaah in worship. [Surah Aal Imraan. Aayah 67]

Neither the Messenger of Allaah nor his companions were upon the path of the people of religions innovations amongst the proponents of Theological Rhetoric nor upon the path of the people of religious innovations amongst the proponents of innovated worship and Soofiyyah; rather he was upon that which Allaah sent him with based on the Qur’aan and Sunnah. [Al-Mukhtaaraat Al-Bahiyyah Min Kutub Shaikhil Islaam Ibn Taymiyyah. 290-291. Slightly paraphrased]