Shaikh ‘Alī Al-Ramlī said:
Be on your guard concerning the young man who is just newly embracing Islām or newly becoming religious.
It may often be the case that a young man’s carrying Khārijī ideas and his being well known for that leads to keeping an eye on him and being on guard against his blowing himself up among people.
But people do not give any thought to someone who is more important than that [to watch out for], [one] whom the Salaf warned against a long time ago: the young man who is just newly embracing Islām or newly becoming religious; the Salaf referred to him as an ‘ajamī [one who is unable to express himself clearly] and a ḥadath [a young one, literally, one whose teeth are still soft].
This one is more dangerous than others with regard to suicide missions due to his combining zeal and ignorance, together with his not being given any thought to–so take notice.
It is this kind that ISIS ensnares.
N.B. Title mine (Trans.)