Is God Perfact? How?

[Tonus]

What do theists mean when they say god is perfect?

As you noted, it's not defined in the Bible in a way that everyone can agree. When I was a theist it meant that God is in full control of his thoughts and actions. Thus, his actions are always his own and not influenced by anything but his own desires and promises. James 3:2 states that a perfect human is "able to keep their whole body in check" while referring to a hypothetical person who is "never at fault in what they say." So a perfect person is in full control of his 'body' with the implication that this means he is in control of his thoughts and actions and able to avoid sin, unlike imperfect humans. On the human level, imperfection could be described as a genetic defect. On the divine level... that's tough to say. We know that angels rebelled against God. Do spirit creatures have DNA?

God's perfection, therefore, does not prevent him from feeling emotions --like anger-- or from taking any particular action --like lashing out violently. But he could not really lash out IN anger, because he has full control of his emotions and his reactions. His every action and decision is calculated because he cannot be swayed by emotion the way imperfect humans are. Thus his actions and decisions and statements should always be consistent and in harmony with the person that he is.