Please be honest?
Just as most students won't study hard if there were no grading system (A, B,..., F), is this same principle applied to religion?
If no, then give reasons,

majority of Christians and muslims won't be Christians or muslims respectively if there was no heaven or hell in their doctrine... in fact.. it would be better.. at least muslims won't be blowing themselves up in the name of Allah.. remove the concept of afterlife from the two Abrahamic religions and you'll watch their numbers decrease.. Christianity would lose 80% of the population.. because unlike Jews, most Christians believe Jesus is their saviour.. saviour from what? hell of course.. except for jw's and few other denominations.. Islam isn't different.. many people who claim to love God say so because they believe in heaven or hell.. i respect all denominations that don't believe in hell but still preach.. at least they don't do it because of the fear of any punishment