Gospel math is pretty simple: Jesus plus nothing equals everything. What this means is that once you have Jesus, you have all you need. It’s really another version of Jesus’ own words: Seek first the kingdom, and all these things will be added to you. Jesus is enough, and not just barely enough, but sufficient, full, complete, entire – if you have Jesus, you don’t need anything else.
Of course, “plus nothing” doesn’t mean that when your kids are hungry after church they just need to be “filled with Jesus” in some sort of spiritual sense – it means that when their bellies are full of food that Dad provided by working faithfully throughout the week, Jesus has fed them. Jesus means all of who Jesus is: creator, sustainer, provider, defender, friend, prophet, priest, king – all of it.
But because in this rich sense Jesus is all we need, the flip side of gospel math is this: Jesus plus anything equals nothing. When we add things to Jesus that He Himself doesn’t bring with Him, we actually lose what we have. Jesus feeds us, but gluttony is not an example of Jesus doing a really good job of feeding us. Gluttony is adding a wrongful love of food to the rightful enjoyment of God’s blessings, exalting the gift over the giver. What we think is addition is in fact a deadly subtraction: Jesus plus gluttony equals idolatry. There is only one way to worship the true God: by worshiping Him alone. First Commandment: No other gods! Any additions are subtractions.
We should be very careful here to note than the Trinity is not an addition to God. Jesus and the Holy Spirit didn’t become part of God; God has always been three-in-one. So in gospel math, “Jesus” is shorthand for the Triune God. When Paul presents Christ as everything, he understands that Christ doesn’t replace the need for God; He is God. The truth of the Trinity is the foundation for gospel math.
Although the idea of gospel math has been around for a while, Pastor Tullian Tchividjian of Coral Ridge Presbyterian Church has recently written a book called Jesus + Nothing = Everything that might be helpful if you want to learn more.