God's main command to us is explicitly stated in Deuteronomy 30:16 (KJV),
I command thee this day to love the LORD
thy God, to walk in his ways, and to keep his commandments and his
statutes and his judgments, that thou mayest live and multiply.
In the same chapter, God emphasizes that this is not some distant, esoteric diktat, but rather a command that we already know and understand because it has been written in our hearts (verse 11-14, KJV),
This commandment which I command thee this day, it is not hidden from thee, neither is it far off. It
is not in heaven ... neither
is it beyond the sea ... But the word is very nigh unto thee, in thy mouth, and in thy heart, that thou mayest do it.
This is why sin causes such guilt and shame; it goes against the very spirit put into us. We must listen to that spirit, and that is achieved through never-ceasing prayer!
