For @structureoftruth I think you’re argument is failing on this last point. And to answer that and @John_Harshman we know God is good because he says he is.
In this argument, there is no, if a, then b. Or if b, then a. It is a=b because God tells us a=b. God doesn’t define good; He is good. We don’t need to evaluate God’s goodness; God is good.
Isaiah 1
“Come now, and let us reason together,”
Says the Lord,
“Though your sins are like scarlet,
They shall be as white as snow;
Though they are red like crimson,
They shall be as wool.
19 If you are willing and obedient,
You shall eat the good of the land;
20 But if you refuse and rebel,
You shall be devoured by the sword”;
For the mouth of the Lord has spoken.
Exodus 3
And God said to Moses, “I AM WHO I AM.” And He said, “Thus you shall say to the children of Israel, ‘I AM has sent me to you.’ ” 15 Moreover God said to Moses, “Thus you shall say to the children of Israel: ‘The Lord God of your fathers, the God of Abraham, the God of Isaac, and the God of Jacob, has sent me to you. This is My name forever, and this is My memorial to all generations.’
Psalm 73:1
Truly God is good to Israel,
To such as are pure in heart.
Psalm 118:1 and Psalm 136:1
Oh, give thanks to the Lord, for He is good!
For His mercy endures forever.
Psalm 143
Deliver me, O Lord, from my enemies;
[e]In You I take shelter.
10 Teach me to do Your will,
For You are my God;
Your Spirit is good.
Lead me in the land of uprightness.
Matthew 19
And behold, a man came up to him, saying, “Teacher, what good deed must I do to have eternal life?” 17 And he said to him, “Why do you ask me about what is good? There is only one who is good. If you would enter life, keep the commandments.”