THE MEANING OF THE WORDS

1. Casting Crowns is an American famous band. Check it out on Wikipedia to find out more.

2. 'All or nothing' is usually said to a degree to stressing on one's seriousness towards an event. All or nothing is two alternatives. You either have it all i.e. both the good and bad things of the object/event, or nothing i.e. you get nothing to gain or lose because you have nothing.
e.g. a mum warning her rebellious teenage son that he either has it all (gets to live at her house, food, shelter, and other benefits but has to obey her rules, or leave the house.)

3. More context is needed in this case. On the surface, when someone says 'sports be in it!', his tone often gives away of his excitement and love for sports (only in the case of sports though). This person is feeling excited for the element of sports is (getting) involved in a certain event or object, or he is suggesting that sports should be taken into consideration of the event or object.
Another instance: when people say 'life be in it' -- as life connotates a lot of possibilities, e.g. the element of unpredictability, happiness, miracle, disappointment, misfortune and so on -- you really have to refer back to the context to know what it means.

Hope it helps :)

casting crowns is a music band

all or nothing refers to a tense situation where any slight mistake may bring overriding victory or waterloo