I am not a Catholic, but I am very confident in my Christianity (non-denominational). My fiancé is Catholic. I attend church regularly, and know what communion is and why we participate in it. I attended my first Catholic service with him, and when I went up to the Catholic priest, I held out my hand, he put a wafer in it, but wouldn’t let go. After an awkward moment, I finally realized I needed to say “amen” before he would give me the wafer. Afterwards, he glared at me and said “now you put it in your mouth” as if I had never participated in communion before. I wanted to apologize after the service and explain that communion is done differently at my church, but my fiancé told me not to because it would make things worse. Did I offend him? If so, how? And why? Should I apologize?
You might know what communion is in your church, but I don’t think you are quite aware of communion in the Catholic Church. For starters, non-Catholics are not permitted to receive communion:
US Catholic Bishops’ Guidelines for the Reception of Communion
For our fellow Christians
Because Catholics believe that the celebration of the Eucharist is a sign of the reality of the oneness of faith, life, and worship, members of those churches with whom we are not yet fully united are ordinarily not admitted to Holy Communion.
Catholics believe that the Eucharist truly and really becomes the body, blood, soul and divinity of Jesus Christ. For someone to receive the Eucharist who does not believe this is sacrilegious.
You did not offend him, you made him immediately suspicious that you were not a Catholic. He was probably afraid that you were not going to consume the host and would discard it.
You do not need to apologize, however you should refrain from receiving communion in the Catholic Church.