Yes, God is everywhere… but he makes His presence in certain places in a very special way… Like in the burning bush in the Old Testament and the Eucharist in the New Testament and even in the person of Jesus Christ… he has a special presence in these places.
Ask your Father in Law if he saw Jesus walking down the road, would he say: “Nah, I don’t want to go over there and see Him, God’s everywhere, I can worship Him in my house, on the toilet, in the library, etc.” That would be sick.
It is the same with the Eucharist, it is really Jesus, and sure we can pray to Jesus at home, but he is Sacramentally present in the Eucharist and His grace comes to us in a special way in the Sacraments that He instituted.
Jesus’ very words were “on this rock I will build my Church” and
“unless ye eat the flesh of the son of man and drink his blood you have no life in you”. Ask your father in law why he would say these things if you can just take the attitude of: “God is everywhere, why listen to these sayings? I can do my thing at home” That is not Christianity that is Pantheism.
We have the Bible and the Words of Christ who told the Church: “Who hears you hears me, Who rejects you rejects me” and he ensures the Church that it will be lead by the Holy Spirit “into all truth”. Now ask him, if the Church is being deceiving and lying to us about Dead Sea Scrolls is Jesus a deceiver? Because Jesus said started this Church and told us to obey it.
God Bless.