We do not advise you to continually read the books of the people of misguidance
Question

I like to read the books and writings of the Raafidis (Shi’ah) and Sufis, and although I have only a little knowledge, praise be to Allaah I am able to pick out their specious arguments for one simple reason, which is that I know that their religion is false and that many of them are extremists or are poor ignorant common folk who deserve pity because they have been deceived and misguided by their leaders. Do you think that I should carry on reading their books or should I stop that?.
Praise be to Allah.The Muslim should protect his beliefs (‘aqeedah) and faith, and be concerned to ensure that his nature and thinking remain sound. He should shun specious arguments and confusion for the sake of his religious commitment and heart, for hearts are weak and specious arguments may deceive them when presented in an attractive manner by the people of innovation and whims and desires, but in fact they are weak and specious arguments. 
Looking at books of innovation and misguidance, or books of shirk and myths, or books of other religions which have long been distorted, or books of heresy and hypocrisy, is not permissible except for the one who is well-versed in Islamic knowledge and whose aim in reading them is to refute them and explain where they went wrong. As for one who is not well-versed in Islamic knowledge reading them, in most cases he will become confused as a result. That has happened to many people, even seekers of knowledge, until it ended in kufr, Allaah forbid. In most cases the one who reads these books thinks that his heart is stronger than the specious arguments presented therein, but then suddenly – when he reads a lot – he finds that his heart has absorbed more of the specious arguments than he ever imagined it would. 
Hence the scholars and the righteous salaf were unanimously agreed that it is haraam to read these books, and Ibn Qudaamah al-Maqdisi wrote an essay entitled Tahreem al-Nazar fi Kutub al-Kalaam (Prohibition on reading the books of kalaam (“Islamic” philosophy)). 
We will quote here the comments of a number of scholars about the prohibition on non-scholars reading these books: 
It says in al-Mawsoo’ah al-Fiqhiyyah (34/185): 
The Hanbalis said: It is not permissible to read the books of the innovators, or books that contain both truth and falsehood, or to narrate them, because that is harmful and adversely affects one’s belief (‘aqeedah). 
Al-Qalyoobi said: It is haraam to read books of fabricated heart-softening reports (raqaa’iq) and fabricated reports of military campaigns (maghaazi). 
End quote. 
In al-Ifaadaat wa’l-Inshadaat (44), al-Shaatibi issued a fatwa saying that it is not permissible for the common folk to read the book of Abu Taalib al-Makki that is entitled Qoot al-Quloob, because of the weird sufi ideas contained in it.  
Al-Haafiz Ibn Hajar said in al-Fath (13/525): 
With regard to this issue it is better to differentiate between the one whose faith has not become strong and deeply-rooted, for whom it is not permissible to read any of these things, and the one whose faith is deeply-rooted, for whom it is permissible, especially when seeking arguments to refute the arguments of the deviant ones. End quote. 
Muhammad Rasheed Rida said in al-Fataawa (1/137): 
Students and the common folk should be prevented from reading these books lest they become confused about their beliefs and the rulings of their religion, lest they become like the crow who tries to learn how to walk like a peacock then forgets his own way of walking and does not even learn how to hop. End quote. 
In Fataawa Noor ‘ala al-Darb (al-Tawheed wa’l-‘Aqeedah/267), Shaykh Ibn ‘Uthaymeen (may Allaah have mercy on him) said:  
With regard to Sufi books, it is not permissible to keep them or read them, except in the case of a person who wants to know what is in them of innovation so that he may refute it, so his reading them is of great benefit, which is to confront and deal with this innovation so that the people will be safe from it. End quote. 
The Standing Committee said in Majallat al-Buhooth al-Islamiyyah (19/138): 
It is haraam for every accountable adult, male or female, to read the books of innovation and misguidance, and magazines which publish myths and false claims and call for deviation from sound morals, unless the one who reads them is able to refute the heresy and deviation contained in them and can advise their authors to mend their ways and can denounce their actions and warn people against their evil. End quote. 
Why expose yourself to evil and specious arguments, when you are safe and have no need of that. Praise Allaah for your being safe and sound, and thank Him for the blessings of guidance and steadfastness; protect that and do not expose it to that which may diminish it.   
Life is too short to be spent in the pursuit of falsehood. Truth, goodness and beneficial knowledge are abundant and if a man were to spend his whole life in studying useful books of knowledge such as books of tafseer, hadeeth, fiqh, heart-softeners, asceticism (zuhd), etiquette, etc, he would not be able to quench his thirst for knowledge, so how about if he is distracted by books of myths and misguidance which are written by the Raafidis and some of the Sufis. 
Listen to the advice of the great scholar Ibn al-Jawzi about paying attention to beneficial knowledge, as he said in Sayd al-Khaatir (54-55): 
As for the scholar, I do not say to him: Focus only on useful knowledge or limit yourself to some of it; 
Rather I say to him: Start with that which is most important, for the wise man is the one who understands how short life is and acts accordingly, even if there is no way to learn everything in one’s lifetime, rather he should do the best he can. 
Then if he gets what he wants of knowledge, he has made provisions for his journey, and if he dies before that, then his intention will help him.  
What is meant is that he should reach his full potential by means of knowledge and action. End quote. 
And Allaah knows best.