What is the battle between the flesh and the spirit described in Galatians?
The sinful nature  wants to do evil, which is just the opposite of what the Spirit wants. And the Spirit gives us desires that are the opposite of what the sinful nature  desires. These two forces are constantly fighting each other, so you are not free to carry out your good intentions. (Galatians 5:17 NLT)
Do you think this means living the pious life of a religious zealot versus the wild partying life of a drunken sinner? Shockingly, that’s wrong! This is not the subject at all. Not even close.
Stop! I am not excusing sin. Sin is sin! Idolatry, swearing, murdering, stealing, lying, coveting, and all the rest (Exodus 20) are all sins. But, that is not the subject of Galatians.
The shocking subject of Galatians is religion!
Read Galatians 5:17 again. Notice the highlighted words: “good intentions.” It is not our evil intentions that are hindered by the war between the spirit and the flesh, but our good intentions. Please read all of Galatians for yourself. The subject is the religious works of the flesh. Read several translations: NIV, NLT, NAS, KJV, GWT, NET, etc…
The Purpose of the Epistle. The purpose of the epistle was to root out the errors of doctrine introduced by the Judaizers and to hold the Galatians to their earlier faith.
(The Bible Book by Book)
I am shocked that you are turning away so soon from God, who called you to himself through the loving mercy of Christ. You are following a different way that pretends to be the Good News but is not the Good News at all. You are being fooled by those who deliberately twist the truth concerning Christ. (Galatians 1:6-7)
Let me explain further. Live your life as your spiritual nature directs you. Then you will never follow through on what your corrupt nature  wants. What your corrupt nature  wants is contrary to what your spiritual nature wants, and what your spiritual nature wants is contrary to what your corrupt nature  wants. They are opposed to each other. As a result, you don’t always do what you intend to do. If your spiritual nature is your guide, you are not subject to Moses’ laws. Now, the effects of the corrupt nature are obvious: illicit sex, perversion, promiscuity, idolatry, drug use, hatred, rivalry, jealousy, angry outbursts, selfish ambition, conflict, factions, envy, drunkenness, wild partying, and similar things. I’ve told you in the past and I’m telling you again that people who do these kinds of things will not inherit the kingdom of God. But the spiritual nature produces love, joy, peace, patience, kindness, goodness, faithfulness, gentleness, and self-control. There are no laws against things like that. Those who belong to Christ Jesus have crucified their corrupt nature along with its passions and desires. (Galatians 5:16-24 GWT)
4561 (sarks) is generally negative, referring to making decisions (actions) according to self – i.e. done apart from faith (independent from God’s inworking). Thus what is “of the flesh (carnal)” is by definition displeasing to the Lord – even things that seem “respectable!” In short, flesh generally relates to unaided human effort, i.e. decisions (actions) that originate from self or are empowered by self. This is carnal (“of the flesh”) and proceeds out of the untouched (unchanged) part of us – i.e. what is not transformed by God.–HELPS™ Word-studies
Shockingly, our good intentions separate us from God…
For since the world began,
no ear has heard
and no eye has seen a God like you,
who works for those who wait for him!
You welcome those who gladly do good,
who follow godly ways.
But you have been very angry with us,
for we are not godly.
We are constant sinners;
how can people like us be saved?
We are all infected and impure with sin.
When we display our righteous deeds,
they are nothing but filthy rags.
Like autumn leaves, we wither and fall,
and our sins sweep us away like the wind.