Okay, think of it this way, will your great great great great great great grandchildren be effected by how good of grades you made in school? It's possible, but not very likely. But will they be effected in your Biblical knowledge? Possibly, yes. I mean, if my great great great great great great great great great great grandfather was a king, do you think that that really matters to me now? No, not really. I mean, other than the fact that that would be kind of cool. But if my family had started being Christians that long ago, would that effect me now? Probably. I mean, if it weren't for them, then right now, I may not be a Christian at all. And not only will it effect their lives and mine, but also it will effect all of our lives even after we've died. Will good grades get us to heaven? No.
So next time you have to make a choice between doing something that might improve your grades, or get you on a sports team, or anything really, and doing something better, then I want to encourage you to do something better. Grades and such may be good for you now, but in the life to come. :)