How many a cappella pop songs exist in the world I don’t know, but “Easter Song” by Glad is likely to be one of the best.  The lead singer is enthrallingly good, both sober and cheerful, while collective vocals fill the bill superbly.  (This on the studio recording.)  A certain restraint is here but so is utter passion, summoned, of course, by the Resurrection.  Too, you’d better believe the song has hooks.