Q2. Why isn't the God of the Christians also the God of those who aren't Christians?
He is their maker and sustainer, but they have not chosen Him as their God.
Scripture Proofs — King James Version
1
Acts 17:24
“God that made the world and all things therein, seeing that he is Lord of heaven and earth, dwelleth not in temples made with hands;”
Psalm 36:6
“Thy righteousness is like the great mountains; thy judgments are a great deep: O LORD, thou preservest man and beast.”
Judges 10:14
“Go and cry unto the gods which ye have chosen; let them deliver you in the time of your tribulation.”