Firstly, it is concerned with one of Islam's main foundations, namely the qualities of al-wala' wa'l-bara', which are two major prerequisites of true faith:
DefenderOfSunnah | June 08, 2009
Al-Wala' is a manifestation of sincere love for Allah, His prophets and the believers;
Al-Bara', on the other hand, is an expression of enmity and hatred towards falsehood and its adherents. Both are evidence of iman.
Secondly, it has been written at a very crucial time: everything has become so mixed up that some Muslims are no longer aware of those qualities which distinguish the believers from the non-believers; their faith has become so weak that they have adopted patterns of behaviour that are absolutely repugnant to a sincere believer; they have taken the disbelievers as their friends, while displaying enmity towards many of the believers by disparaging their character and degrading them -DefenderOfSunnah