Reference: Fataawa Islaamiyyah – Volume 1, Page 17
Question: We often hear that the Last Hour will not come to pass until Islaam prevails on Earth. But we also hear that it will come to pass when there is no one who says «Laa ilaaha il-Allaah» (There is none [truly] worthy of worship except Allaah [alone]). How can we reconcile between the two statements?
Response: Both statements are correct. It is authentically reported that the Prophet (sal-Allaahu ‘alayhi wa sallam) said that the Last Hour will not come to pass until ‘Eesaa (Jesus) the son of Maryam (Mary), whom Allaah saved from evil, comes down to Earth, kills the Dajjaal and the swine and breaks the cross. During his era, wealth will become in abundance. He will waive the Jizyah and accept from people only Islaam or the sword. Allaah will abolish during his era all religions except Islaam. Prostration will be to Allaah alone. This indicated clearly that Islaam during ‘Eesaa’s (‘alayhis-salaam) time, will prevail on Earth, with no other faith beside it.
It is also authentically reported that the Last Hour will come to pass while only evil people are alive. Allaah (Subhaanahu wa Ta’aala) will send a pleasant breeze after the death of ‘Eesaa (‘alayhis-salaam), and after the sun rises from the west. This breeze will collect the soul of every believer, man and woman. After which there will remain alive only evil people upon whom the Last Hour shall come to pass.