Reason and the Greatest Commandment

2021 Sep 30

In Matthew 22:34-40, Jesus teaches that the greatest commandment is to love God. He also taught that the next greatest was to love your neighbor as yourself. There are several aspects of this that are fascinating.


For this story in Matthew note, there are parallel passages in Mark note and Luke note with interesting comparisons and contrasts. All of them show that Jesus and the theologians of his day were in agreement about the answer. Mark and Luke are different from Matthew because of changed words in the quote. Luke is different from the others because of swapped roles (of the questioner and who answers).

“On one occasion an expert in the law stood up to test Jesus. “Teacher,” he asked, “what must I do to inherit eternal life?”

“What is written in the Law?” he replied. “How do you read it?”

He answered, “ ‘Love the Lord your God with all your heart and with all your soul and with all your strength and with all your mind’; and, ‘Love your neighbor as yourself.’”

“You have answered correctly,” Jesus replied. “Do this and you will live.””

Luke 10:25-28 NIV

“One of the teachers of the law came and heard them debating. Noticing that Jesus had given them a good answer, he asked him, “Of all the commandments, which is the most important?”

“The most important one,” answered Jesus, “is this: ‘Hear, O Israel: The Lord our God, the Lord is one. Love the Lord your God with all your heart and with all your soul and with all your mind and with all your strength.’ The second is this: ‘Love your neighbor as yourself.’ There is no commandment greater than these.”

“Well said, teacher,” the man replied. “You are right in saying that God is one and there is no other but him. To love him with all your heart, with all your understanding and with all your strength, and to love your neighbor as yourself is more important than all burnt offerings and sacrifices.””

Mark 12:28-33 NIV

“Hearing that Jesus had silenced the Sadducees, the Pharisees got together. One of them, an expert in the law, tested him with this question: “Teacher, which is the greatest commandment in the Law?”

Jesus replied: “ ‘Love the Lord your God with all your heart and with all your soul and with all your mind.’ This is the first and greatest commandment. And the second is like it: ‘Love your neighbor as yourself.’ All the Law and the Prophets hang on these two commandments.””

Matthew 22:34-40 NIV

quoting from:


“Hear, O Israel: The Lord our God, the Lord is one. Love the Lord your God with all your heart and with all your soul and with all your strength.”

Deuteronomy 6:4-5 NIV


““ ‘Do not seek revenge or bear a grudge against anyone among your people, but love your neighbor as yourself. I am the Lord.”

Leviticus 19:18 NIV

Is there a problem because of the differences? I don’t think so. It is likely that this topic came up more than once since it is an important point of teaching. Jesus and other teachers were in agreement on these fundamentals so it was probably a jumping off place multiple times for discussion of related things. (For instance in Luke it segues into the Good Samaritan story.)

Jesus quotes from Deuteronomy, where the commandment originally says to love God with all your heart and your soul and your strength. However in Matthew, the quote of Jesus is changed to say that we are to love God with all our heart and soul and mind.

Is this a mistake? Again, I don’t think so. The Mark and Luke versions of the story both add mind while still including the original word strength. It may be that there was some relatedness of thinking in the ideas of the two words. note Remember that both Mark and Luke had agreement from dogmatic local religious experts that the answer was correct.

The first commandment in Deuteronomy 6:4-5 is quoted a few times in the Old Testament, but strength is dropped in these quotes (only heart and soul are included). Mark and Luke are the only places that include strength. Matthew and Mark add mind.

Interestingly also note that in his quote by his own authority, Jesus changed the greatest commandment that God gave to the Jews. Even if this addition of mind was agreeable to authorities during the time of Jesus, Jesus did modify a primary command of God. Implicitly then by this Jesus established his equivalency to God.

Love through Strength

The original command emphasized effort because strength was included. This command was originally given in the context of enumerating social and religious laws for Israel. Laws are for regulating behavior - an aspect that requires effort. It takes strength to modify behavior from what would otherwise come naturally. Note however that compliance to law generally doesn’t require thinking as much as it requires doing.

Usually when there are loopholes, judges will develop case law to cover new situations. The judges have to think to develop the case law, but afterward the citizens just need strength again to follow the new rules.

Love by Mind and Reason

However, Jesus changes the command to elevate reason because reason comes from the mind. Critically however, Jesus does not elevate reason to the highest place. He placed reason under the authority of love, and specifically under love for God.

Reason is good only when it is motivated by and under the control of what is good. I started thinking about all this from something I heard Jordan B Peterson say:

"I read Milton as a warning that when reason is elevated to the highest place that hell follows quickly behind. For example: there is nothing more rational than Marxism. All the axioms are wrong, but all of the logic that flows from the axioms is perfectly logical."   JBP Podcast S4: E48 at 52:37

Marxism has been justified by its rationality and it makes the appearance to be for good, but in practice it is not motivated by love. The results were demonstrated in the evils of the 20th century that reached historical excesses of killing. That costly experiment proved the axioms were wrong.

Reason without love is terrible. This has sobering import for those that see the world as only materialistic because if that were true, then there is then no objective standard for moderating cold reason into care for other people.

Reason and Love

However, Jesus changed the greatest command to bring reason into the service of love. Understanding of how it serves love comes through the second command to love your neighbor. Love for God motivates us to love our neighbor.

Note that there is not much that we can do to love God directly because God does not need anything from us. What can we give God that God does not already have far beyond what we can produce? However, we can use our mind to think about how to live in a way that loves others, and use our strength to live this way. This is clearly what God wants of us and this is something that we can give God.

This line of reasoning which is motivated by love bypasses any loopholes or attempts to avoid doing the right thing. That is why all the law hangs on these two commandments! (See also The Commands of Jesus.)

God is rational

The laws God gave to the Israelites were stable by their nature; this showed them that God's nature was consistent. By this they could also infer that the world God made was regular and stable. Reason then is also plausible in this kind of world because logic can be predictable and consistent. (In contrast, in a capricious world nobody could be sure that logic would come to the same result every time.) So God created a context that encouraged reason. note

In a world that is not stable, a "reasoned" conclusion might randomly later change. Therefore, in an unstable world reason is useless.


This is actually one of the problems of some of "the universe was made by math" hypotheses of Hawking, Krauss and Tegmark. First they suggest that because math exists which describes the universe, that the universe did come into existence from the math.

Yes, math can describe the function of a universe like ours. However, it only describes a universe like ours if there are mindful limits added beforehand into the formulas. If the solutions to the general equations are not limited to what is reasonable, the mathematical outcome is an infinite quantity of unreasonable and capricious solutions to the equations. In this case it is infinitely most likely that the worlds described would be unstable, irrational, not consistent.

Another problem with the "universe from math" ideas is that math is intellectual and it only comes from minds. Therefore the ideas of their theory suggest that a mind must have been needed before the universe existed. In that case the math is an artifact of the mind that thought it, and the universe therefore came from this mind.

(See also Book: Return of the God Hypothesis.)

Jesus then also elevated reason in his teaching of the greatest commandment. Critically however, what he encouraged was all aspects of reason that were compatible with love.

God wants us to think, using our mind and reason to grow and become like him in love. A thinking Christian asks questions without fear because God is rational and has good answers for spiritual questions. note

God has good answers for philosophical questions as well. That is, the spiritual truths and the pragmatics of living meet intellectually and have fulfilling answers. There are still hard questions and we might not be able to answer all questions, but it is OK to admit a position of not knowing everything.

God is intellectual! As the maker of this world, God made the world to be discoverable, and gave us curiosity about our world. A scientist has good reason to think it is possible to learn things about our world because God is consistent, God made a world that has internal consistency, and he made it understandable, reasonable and discoverable. Many early pioneers of science like Isaac Newton certainly were motivated to their work by this line of thinking. Science arguably came into existence because of this thinking. (See also Science and the Lawgiver)

Finally also, a Christ-follower living out love is not a weak romantic. This life is not for wimps. It takes real strength to do the right thing and to do well for others. Some times there are hard choices to be made to come to a loving plan of action. This kind of love brings out the best in people, including the best in both femininity and masculinity.

There is no greater or better challenge for our reason and strength than to follow this greatest of commandments as Jesus teaches it.