Spiritual growth happens in the body.
For many of us, the idea that the brain is the locus of the mind seems obvious. But less obvious is the notion that the body is the locus of the brain. But perhaps even less obvious is that the whole body, including the brain, is the mind. Scott Adams writes:
I am sure you have noticed that your mental state is deeply influenced by diet, exercise, sleep, sex, stress, and lots more. And I’m sure you make some effort to do those things the right way when you can. But if you think those actions are influencing only how you feel, and not your actual thoughts, you don’t understand the basic nature of human beings. And this is the key takeaway:
The source of your thoughts is your body, not your brain.
When I am not feeling good, I don’t ask my brain to fix things on its own. I manipulate my environment until my thoughts change. That’s because I see my body as the user interface to my brain. I don’t let my brain think whatever it randomly wants to think. I constrain it to productive thoughts by manipulating my environment.
Similarly, the Bible teaches that the whole of the human body should be conceived of as the locus of spiritual growth:
Romans 6:13-19 ESV Do not present your members to sin as instruments for unrighteousness, but present yourselves to God as those who have been brought from death to life, and your members to God as instruments for righteousness. (14) For sin will have no dominion over you, since you are not under law but under grace. (15) What then? Are we to sin because we are not under law but under grace? By no means! (16) Do you not know that if you present yourselves to anyone as obedient slaves, you are slaves of the one whom you obey, either of sin, which leads to death, or of obedience, which leads to righteousness? (17) But thanks be to God, that you who were once slaves of sin have become obedient from the heart to the standard of teaching to which you were committed, (18) and, having been set free from sin, have become slaves of righteousness. (19) I am speaking in human terms, because of your natural limitations. For just as you once presented your members as slaves to impurity and to lawlessness leading to more lawlessness, so now present your members as slaves to righteousness leading to sanctification.
The answer to the question of spiritual growth lies, uncomfortably for many of us, precisely in our conception, treatment, and use of our bodies. Why is this? Because while each of us experiences the self in a somewhat disintegrated fashion, each of us is, indeed, a single person. So there is no spiritual growth without attendance to the body.