You may want to remind them of when the Pharasees accused Jesus of driving out the demons using the power of Satan and how he replied that a house divided cannot stand.
That being the case, if we are the Church of Satan, why do we begin every prayer in the name of the Father, the Son and the Holy Spirit? This is a simple thing that is recognized immediately as being extremely Catholic. Certainly, if we, as individual Catholics or as a Church, intended to be giving honor to Satan, we wouldn’t be calling out to the enemy.
Then, you may want to ask for one simple (and they need to pick one, but only one) example of how what we believe as Catholics is contrary to the beauty of all that Christ taught. Tell them that you would like to begin the discussion of this one element with a prayer said by the both of you. That prayer is that you ask the Holy Spirit to guide you to the fullness of the truth as given to us from the Father through His son, Jesus Christ. Tell him that you would like to establish as ground rules that you are both seeking to best know and understand God and that you are not interested in engaging in a battle to determine which of you are “right” because the ultimate goal is to find the truth in God.
Then, hear his concern about the teaching of the Catholic Church. Keep it on one topic at a time and never worry if you are unable to answer the question immediately. If you don’t know the answer, tell him / them that you’ll get back with an answer, you just don’t know it right now. If the answers become personal jibes, remind them that you are interested in discussing God’s truth, so that all Glory and Honor might be given unto God. You are not interested in making personal attacks and you would appreciate it if they would return to the ground rules you had agreed to in the beginning.
Keep things Charitable and pray for charity in return. You might be amazed to find that the most fervent detractors of Catholicism have the potential of becoming the most faithful followers once they learn that all they thought they hated about the Church was based on a false understanding of what we believe.
Good luck and God Bless,
CARose