Paul uses the word spirit (pneuma) six times in Romans 8:12-17, and he uses it in multiple ways. They don't all refer to God's Spirit, not even when most translations capitalize the word. There's a chiasm in these verses that might help you see the idea that Paul was trying to explain.

A - V12-13 - Killing the flesh per God’s Spirit leads to life
B - V14 - Spirit of God reveals sons of God
C - V15 - Spirit of slavery vs spirit of adoption as sons
B - V16 - Spirit of God reveals children of God
A - V17 - Suffering in flesh per God’s Son leads to life

https://tube.ttn.place/v/8NV6Ac

A Chiasm on Sons and Slaves in Romans 8:12-17
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A Chiasm on Sons and Slaves in Romans 8:12-17

⁣Romans 8:12-17 ESV 12 So then, brothers, we are debtors, not to the flesh, to live according to the flesh. 13 For if you live according to the flesh you will die, but if by the Spirit you put to death the deeds of the