Should a monotheistic God ever be considered good or great?

Newton's first law States that:

An object at rest will remain at rest unless acted on by an unbalanced force. An object in motion continues in motion with the same speed and in the same direction unless acted upon by an unbalanced force. 

Newton's first law essentially states that a net external forces is needed to induce change in the state of either a moving or stationary object.

If you see analogy for God then God is the sole source of power/cause in a monotheistic universe. Thus there is no outside or external force to induce change in God.

Another reason God can't change is because God is akin to infinity in a monotheistic world. Add or subtract anything to infinity and it remains infinity.

Philosophers  have discussed it various times how essential character of God can't change.

The opening lines of Isavasya Upanishad states this:

”Om Purnamadah Purnamidam Purnat Purnamudachyate

Purnasya Purnamadaya Purnamevavashisyate

Om, shanti, shanti, shanti.”

Translation: ”THAT is infinite, THIS is infinite; From That, This comes. THIS added or removed from THAT, the Infinite remains as Infinite. Om, peace, peace, peace.”

You could also see God as completeness.

Also, changing the nature of God will create ethical issues.