This is like the existence of devils among jinn and humankind: Allah raises the ranks of the people (1) of faith through their opposition to these devils and their striving against them, even though their existence is a trial for those whom they lead astray and misguide.

This is illustrated by the words of Allah Most High:

“We have made their number only a trial for those who disbelieve, so that those given the Scripture may become certain and those who believe may increase in faith.” [Surah al-Muddaththir: 31]

And His words:

“We appointed the direction of prayer which you formerly faced only to know who would follow the Messenger and who would turn back on his heels.” [Surah al-Baqarah: 143]

And the words of Moses:

“This is only Your trial, by which You lead astray whom You will and guide whom You will.” [Surah al-A‘rāf: 155]

And His words:

“We are sending the she-camel as a trial for them.” [Surah al-Qamar: 27]

And His words:

“We never sent a messenger or prophet before you but that, when he recited, Satan cast something into his recitation. Yet Allah removes what Satan casts, and then Allah establishes His verses. Allah is All-Knowing, All-Wise. This is so that He may make what Satan casts a trial for those whose hearts are diseased and those whose hearts are hardened. Indeed, the wrongdoers are in far-reaching dissension. And so that those given knowledge may know that it is the truth from your Lord, believe in it, and have their hearts humbly submit to it. Indeed, Allah guides those who believe to a straight path.” [Surah al-Hajj: 52 - 54]