Begin By Learning The Fundamentals Of Ahlus-Sunnah wal-Jamaa’ah
By Abu ‘Abdillaah Ahmad bin Muhammad ash-Shihhee
This is just an excerpt of an article which you can read from here insha’Allaah: Begin by Learning the Fundamentals Of Ahlus-Sunnah wal-Jamaa’ah
Know, may Allaah grant you the ability to obey Him that I do not mean by “Fundamentals”, the three categories of Tawheed only. Rather I intended that first, and secondly I meant by it, the other fundamentals, which Ahlus-Sunnah wal-Jamaa’ah have agreed on and due to which they have separated themselves from the people of innovation and sects, such as the (the principles of):
Showing al-Walaa wal-Baraa (Loyalty and Disavowment), commanding the good and forbidding the evil, the (correct) stance towards the Sahaabah (Companions) – respecting and defending them, the position with respect to the Leaders, the stance with regard to the transgressors and sinners, and the position towards the People of Innovation – speaking against them and dealing with them.
This goes as well for all the other fundamentals that Ahlus-Sunnah wal-Jamaa’ah have agreed upon and which they have put in their books on Creed, in order to clarify the truth and separate themselves from the people of deviation, calamities, vain desires and division – even though the source for some of these principles may be related to actions and not Creed. 
So if you have gotten a firm grasp in understanding these points and fundamentals, then, by the Will of Allaah, you will be fortified against many of the misconceptions that are gushing throughout the Islamic world.
But when many of those who have repented become negligent in this matter and do not initiate their repentance by learning the fundamentals and methodology of Ahlus-Sunnah wal-Jamaa’ah, they become confused and lost with just the slightest of misconceptions! We ask Allaah to save and protect us!
Whoever reflects on the condition of these people, will find many instances and examples for this confusion and shakiness, amongst which are:
The First Example:
You find the person who has turned to the Way of the Salaf, in the beginning, strict and determined to keep far away from the people of innovation and sects.
This lasts for some time, but then he is presented a misconception from one who clothes himself in the garb of Salafiyyah, which in brief is:
1. “Staying away from the people of innovation and not sitting or mixing with them is not correct.”
2. “This causes many benefits to be missed out on.”
3. “There is no one after Allaah’s Messenger (sall-Allaahu ‘alayhi wa sallam) that is infallible. Even the Sahaabah made mistakes…”
And he does not hear these doubt-raising arguments except that you see his heart become diseased. And you see him drinking (from) this misconception faster than he drinks water. And lo and behold, thereafter, he begins to mix and associate with the people of innovation, becoming soft and easy-going with the principles of Salafiyyah, while doing this in the name of Salafiyyah!
This confusion only came about due to his failure to engage in learning the Qur’aan and the Sunnah, according to the understanding of the Salaf (Predecessors) of this Ummah. And it was due to his failure to study the Fundamentals of Ahlus-Sunnah wal-Jamaa’ah. This is since if he were to have devoted time to seeking of knowledge, he would have known that this misconception is false and at variance with the position of Ahlus-Sunnah wal Jamaa’ah towards the people of desires and innovation, in the past and present.
And he would have known that the statement of this false-claimer (to Salafiyyah): “There is no one after Allaah’s Messenger that is infallible” and “everyone makes mistakes” are words of truth, but by which falsehood is intended. This is because when anyone amongst Ahlus-Sunnah wal-Jamaa’ah – from the Sahaabah and those who followed after them in goodness – made an error, their error did not come as a result of following desires, or failing to follow the narrations or distorting the texts or chasing after what is unclear and ambiguous from these texts, as is the case with the people of innovation. Rather, their error would come due to one of them not being aware of the proof for it or his knowing about it yet not considering it to be authentic, or any of the other reasons for which they have an excuse.
The following saying of Allaah’s Messenger (sall-Allaahu ‘alayhi wa sallam) was revealed concerning them and concerning those who follow them in goodness:
“When the judge issues a ruling, making Ijtihaad in the matter and is correct, he gets two rewards. And if he gives a ruling, making Ijtihaad in the matter, and is mistaken, he gets (only) one reward.” [Reported by al-Bukhaaree & Muslim]
This is contrary to the People of Innovation and Sects, since they do not have any concern for the narrations, and they give precedence to their intellects over the texts from the Book and the Sunnah! Rather, they establish principles that are in opposition to the principles of Ahlus-Sunnah wal-Jamaa’ah! So these kinds of people are not to be sought excuses for, as that false-claimer (to Salafiyyah) had made excuses for them. And no one includes them in the same row as that of Ahlus-Sunnah wal-Jamaa’ah except for someone who is ignorant or an arrogant innovator!
Read the second example from the complete article from here: Begin by Learning the Fundamentals Of Ahlus-Sunnah wal-Jamaa’ah
Taken from: Al-Wasaayah as-Saniyyah, Pgs. 17-27
 Translator’s Note: An example of this point would be the inclusion of the issue of wiping over the socks for ablution. The source for this issue stems from action, yet many of the scholars of the past, including Ahmed bin Hanbal put it in their books on Creed, since by it they distinguished themselves from the people of desires and innovation, who rejected this aspect of the Sunnah based on it not conforming to their intellects.