Ephesians 6:4
Fathers, do not provoke your children to anger, but bring them up in the discipline and instruction of the Lord.
We expressly see the points stated by Paul and they are one of bringing a child up in the instruction of the Lord, as a mother and father guides their child in the way of understanding that they may gain wisdom and understanding, so it is even more important for that child to be brought ONLY in the instruction of the Lord, to teach other religions and to teach your son or daughter idolatry which we know is in defiance to the word of God.
Proverbs 22:6
Train a child in the way he should go, and when he is old he will not turn from it.
What are you training your child in? to expose them to falsities which WILL lead to destruction or to bring in up in the knowledge of the truth, of the only Sovereign and Omnipotent God?
Exodus 20:3
“You shall have no other gods before me.
In Exodus the Lord clearly stated that you shall not have other gods before him, to teach of other religions and their beliefs is not only teaching them corruption but you are serving your children to gods that are not even gods!
As the Lord said, in his truth.
Isaiah 45:5
I am the LORD, and there is no other, besides me there is no God; I equip you, though you do not know me,
Ephesians 4:14
so that we may no longer be children, tossed to and fro by the waves and carried about by every wind of doctrine, by human cunning, by craftiness in deceitful schemes.
As we mature in our walk we are meant to become grounded and mature in the faith, not tossed to and fro by every wind of doctrine, why would be feed our kids lies and expose them to 'strange' religions, as to cause them to stumble and to toss them to and fro by human cunning and by craftiness in deceitful schemes.
Deuteronomy 4:9
Only be careful, and watch yourselves closely so that you do not forget the things your eyes have seen or let them slip from your heart as long as you live. Teach them to your children and to their children after them.
We are to feed our children the truth of the word, not lies, to bring them up in the knowledge of the Living God not idols.