The songs in U2 have a sort of ambiguity about them. For example: (One for each decade)
With or Without You; 1980s (1987): The 'you' could be interpreted as your lover, family, friends or God as it doesn't directly interpret who 'you' can be, leaving the audience to use it in their own way.
Beautiful Day; 2000s (2000): The lyrics suggest something lost or frustrating, as it says the "traffic is stuck...you not moving anywhere" and in the second verse he mentions the feel of entrapment as he is "in the maze of her imagination". So in a way, U2 could be trying to send a message to forget your troubles as it is a "beautiful day". However (with U2 tradition), there is a hidden Biblical reference- a sentence to "see the bird with the leaf in her mouth/After the flood all the colours came out" which is an obvious reference to the 40 day/night flood.
One; 1990s (1992) : I'm not really sure (hey I'm just 15- my interpretation skills are still a bit iffy) but the lyric "One but we're not the same" could possibly refer to the Trinity or could be a rallying call.
There plenty of others- in fact every U2 album has a sort of Biblical allegory or reference within the lyrics. For detailed lyric interpretation check U2MOL (Google it if you have to).
(Note bad for a 15 year old eh?