Manic Street Preachers - If You Tolerate this Your Children will be Next Lyrics Meaning

A song about the Spanish civil war inspired by the song 'Spanish Bombs', on the Clash album London Calling.
It is sung from the point of view of someone considering joining the fight against the facist's, but the author's inner termoil, or fear, of doing so.
Las Ramblas is an area of Barcelona, so we have to assume this is where the person in question lives. The statememt 'if you tolerate this', etc. is obvious, it must be stopped now, or not at all. We know now it wasn't.