Nerdy joke

Via Ed Brayton:

Jesus and his disciples were walking around one day, when Jesus said, "The Kingdom of Heaven is like 3x squared plus 8x minus 9." The disciples looked very puzzled, and finally asked Peter, "What on earth does Jesus mean: 'the Kingdom of Heaven is like 3x squared plus 8x minus 9?'" Peter said, "Don't worry. It's just another one of his parabolas."

In case you're wondering, it's a simple joke. You don't need to get to its roots in order to understand it.