When Jesus was asked about the greatest commandment, he was being asked what had, by that time, become a fairly standard question that rabbis would ask one another. This teacher of the law, if nothing else, at least recognized the quality teaching of Jesus. Jesus’ response, while not phrased in this particular way, had begun to become a somewhat standard response, with two notable exceptions:
First, Jesus declares that to “love your neighbor as yourself” is also the greatest commandment. The standard rabbinical reply was that the Shema (the first commandment), was the greatest, and that one loved God best by working to fulfill the law. The law was best summarized by the command to “love your neighbor as yourself.” Jesus elevates it. When he declares it is “second” he is not declaring it is second in priority. He is merely indicating that there is another command that is inseparable from the first. This reaches back, again, to Genesis 1.
When God created humans, God created them in the image of God. This does not mean we bear physical resemblance to (for God is Spirit), nor, I would argue, does it mean we have a measure of traits that also belong to God. Instead, Genesis 1 as part of the Torah (law) is intended to combat idolatry, Israel’s biggest struggle prior to the exile. The reason idolatry is wrong is because it creates a second image of God, when we, as humans, already exist as this image. This is behind the teacher of the law’s response to Jesus that “to love your neighbor as yourself is more important than all burnt offerings and sacrifices.” We worship God best through loving our neighbors as ourselves.
The second addition Jesus gives to the standard response is the addition of the word “mind.” The Shema command of Deuteronomy indicates the love of God with all your heart, soul (being/identity), and strength. Jesus adds to it to love God with all your mind. Again, the teacher of the law picks up on that, renaming it “understanding” in English translations. To love God properly is not to turn of your brain and stop thinking. Nor is it to allow yourself to fall into a “holy frenzy” where you lose sense of self and are unaware of what is happening, as is the case with some. No, to love God fully is to be fully engaged with all of your being, including your mind. When you study God’s word, when you ask hard questions, when you wonder, and yes even when you doubt, you are expressing a love for God with your whole being.