Second perhaps only to 'Like a Virgin' in defining Madonna's career, 'Vogue' has etched a place in the dance-floor lexicon, where it remains more than two decades later. 'Like a Prayer' is indeed a pop-music prayer, answered for the ages. Instead, we love it for its dance mandate, its gospel strain and the passion that Madonna's vocals embody.

It's amazing that a number about so many heavy things - religious guilt compounded by one's devotion to God, mixed with the ideal of doing the right thing and, of course, the thrust of sexual pleasure - doesn't (and really never did) carry the burden of being an Important Song. It's what, more or less, spawned critics' declaration that Madonna was the high priestess of reinvention. Today, pop stars are lucky to land a song that leads to even half the longevity that 'Like a Prayer' has seen. 1 and has since been listed on Rolling Stone's and Blender's lists of the greatest songs of all time. Critics praised the song, which spent three weeks at No. Madonna shrugged off the contention, and rightfully so. The American Family Association condemned it, and Pepsi, which used 'Like a Prayer' in a $5 million advertising deal with Madonna, dropped the singer's campaign. It seems tame compared to Madge's later videos, but the religious controversy resulted in protests. Its video, directed by frequent early-Madonna collaborator Mary Lambert, depicts white supremacy, an interracial romance and Madonna crooning in front of Ku Klux Klan-style burning crosses. It helps, too, that the song sparked a flame of controversy. It's just '80s enough to have catapulted to ubiquity within weeks of its release, but it's timeless enough to remain a staple of contemporary-flashback radio. The hum of the choir at the start crescendos in a way that still demands everyone leap from their seats. That's because 'Like a Prayer' is among the best pop songs of all time. If you're in a karaoke bar, someone better grab that microphone pronto, before another cross erupts into flames as penance for your pop-music sins. If you're in public when it begins on your iPod, shove your hands in your pockets immediately to keep from undulating like a member of the song's gospel choir. Wherever you are, the opening pings of the organ in 'Like a Prayer' are like a call to action.

Madonna discography singles