Tennant declaró en una entrevista que escribió la letra purgando sus emociones en un momento de enojo, aunque nunca pensó que fuera algo demasiado serio.1? En ella, evoca algunas impresiones que sacó de su estancia en la escuela secundaria católica St Cuthbert's de Newcastle upon Tyne.
Al final de la canción, Tennant recita una parte del Confiteor, y se incluyen pistas de sonidos grabados en lugares como la Catedral de Westminster. En el videoclip se echó mano de imágenes religiosas para reforzar la sensación de la canción.
Me gustan los arreglos y la letra, como comenta en su opinión el artista, es empatía con un momento de molestia, considero que es una canción con un poco de ironía, solo que también es agradable para quienes vivimos esta época.
When I look back upon my life It's always with a sense of shame I've always been the one to blame For everything I long to do No matter when or where or who Has one thing in common, too It's a, it's a, it's a, it's a sin It's a sin Everything I've ever done Everything I ever do Every place I've ever been Everywhere I'm going to It's a sin At school they taught me how to be So pure in thought and word and deed They didn't quite succeed For everything I long to do No matter when or where or who Has one thing in common, too It's a, it's a, it's a, it's a sin It's a sin Everything I've ever done Everything I ever do Every place I've ever been Everywhere I'm going to It's a sin Father, forgive me, I tried not to do it Turned over a new leaf, then tore right through it Whatever you taught me, I didn't believe it Father, you fought me, 'cause I didn't care And I still don't understand So I look back upon my life Forever with a sense of shame I've always been the one to blame For everything I long to do No matter when or where or who Has one thing in common, too It's a, it's a, it's a, it's a sin It's a sin Everything I've ever done Everything I ever do Every place I've ever been Everywhere I'm going to It's a sin It's a, it's a, it's a, it's a sin It's a, it's a, it's a, it's a sin