Wa iyyaak
Our teacher mentions this very often, and he mostly does a "heart softeners" book at the end of the day in his lessons, due to this reason. He mentioned that there are many people who attribute themselves to the correct `aqeedah, when in fact they have not understood `aqeedah. Like for example a person says "You should place complete trust in Allaah and this is from completing one's tawheed", yet he fails to have acted upon his belief, because if he did act upon what his tongue claims then there will be nothing he would worry about in terms of this dunya, and he would leave everything in the hands of Allaah, and how many are those who affiliate themselves to those people who have understood Tawheed Asmaa wal sifaat? Yet their actions seem to contradict their beliefs. And how many of us, when afflicted with trials, we fail to turn back to Allaah? And how many of us, when Allaah afflicts us with harm, we turn away from Allaah and end up in sins?
And all this comes down to the diseases of the heart, indeed it is this heart, if it is sound, then the entire body is sound.
Our 'Ustaadh also mentioned many of the people who affiliate themselves to the correct `aqeedah and the sunnah of the Messenger of Allaah :saw2: are the ones whose hearts are indeed rock hard. And you see these sort of people to be from those who are harsh towards the believers, lacking in adaab, even showing baraa' towards the believers (if not in the apparent, then atleast in their hearts; due to jealousy) etc.
So he mentioned that a person who is new to islaam, he should be taught about Tawheed, and at the same time be reminded about Eemaan based things (like the aakhira, death, jahannam, jannah etc) and this is from the ways of building Eemaan in a person's heart, bi idhnillaah. And this was the way of the Messenger of Allaah :saw2:. He even mentioned that the students of knowledge, are in need of such heart softeners, as the knowledge they gain might increase them in kibr and `ujb (thinking high of one's self). And indeed these two are from the greatest disease of the heart
Ibn Qayyim rahimahullaah said: The diseases of the heart are greater than drinking alcohol, zinaa' and running away from the battlefield on the day of a battle (this is from the seven destroyers).