We all talk of Allah and the Day of Judgement. But do we really have a strong faith is a moot question! It is only Satan (and his ilk) that is a touchstone for testing the humans.

If you take Allah's name with implicit faith, then why you don't have confidence in His promises. If, unfortunately, you have accepted the fears that Satan has put in you mind, then you will be rendered a momin only in the namesake. If you have a strong belief in the existence of the Heaven, then why you don't make a sincere effort to earn a place in it! Why don't you try to avoid going to the Hell as Retribution for the evil deeds committed under the spell of Satan!

Wa ma kaana lahu alaihim min sultanin illa lenalama mai yaumenu bil aakhirate mimman huwa minha fi shak

And there is not for him any authority over them , save that We would know (distinguish) him who believeth in the hereafter, from him who is in doubt concerning it.----Saba 21

You see that a particular lady has claims of piety. Satan approaches her in the garb of a human being and says, ' Madam! You have become old-fashioned and retrograde! You have covered yourself in such a clumsy chadar (shawl)'. When you happen to see the lady a second time, she will not look much different from gentlemen! Satan creates such doubts, fears and changes in the human beings.

Definitely, the purpose of the creation of Satan is to test the human beings as to their determination to be steadfast on the right path. Those who are fickle minded and susceptible to be led astray by Satan are also tested by Satan! Thus Allah gets a proof of who is momin (pious) and who is fajir (hypocrite.)