God is love. God is just. God is merciful.

[John V]

So, your god's justice is subject to his opinion?

Yes. There's not some objective law outside of and superior to God to which he must submit.

That makes it subjective. And since most people talk about objective laws when considering what is just and what isn't, your god's "subjective justice" is meaningless.

All laws are subjective.

He could just as easily be of the opinion that everyone should pay the same penalty regardless of actions and call that justice.

Yep.