"And this worldly life is not but diversion and amusement," meaning: the people of this world are people of diversion and amusement; that is, the polytheists are the people of this world who do not acknowledge the Hereafter. "But indeed, the home of the Hereafter," meaning: Paradise, "it is the [eternal] life," meaning: its people will remain therein and will not die. "If only they knew," meaning: had the polytheists known, they would have known that the Hereafter is better than this world.