We have to be careful here to understand what he’s talking about. Let’s start by answering the OP’s question very directly and then I’ll try to give a theological analysis of this statement by the Holy Father.
Answer to the young poster’s questions is simple. One cannot be Catholic and Protestant at the same time. One must be either Catholic or Baptist. The moral obligation here is to follow the fullness of truth which subsists only in the Catholic Church; therefore, the moral obligation is to become a Catholic, since obviously grace is pointing you in that direction. We have a moral duty to follow grace.
Now to the Holy Father’s comment on unity and diversity. An Ecumenism of Return meant that a non-Catholic who became a Catholic had to repudiate his former faith community. The Holy Father is saying that this is not necessary. Because you leave the Baptist church to become a Catholic does not mean that you turn against the Baptist. It does not mean that you forget all the good things that you learned as a Baptist or that you stop doing them, even if they are things that Catholics would not normally do.
I can give an example from my experience. I was born Jewish. Today, I’m Catholic. I do not badmouth Judaism, nor do I tolerate it. I’m Catholic because of Judaism. Everything I learned about God I learned from Judaism. My desire to know more about him was given to me by Judaism. As I followed this desire, it led me to Christianity. I became a Christian, because Judaism taught me to observe the commands of the Lord. One of them is to go where God leads. Just as he led our father Abraham, he led me right into Catholicism. I simply did what Abraham would have done. I followed.
I still attend the services on the High Holy Days with my family and sit down to Seder with my siblings and their families. I don’t do it because I need it for salvation, but because I need my family and friends. I am a part of their lives and they are a part of mine.
If I were a Baptist becoming Catholic, I would not worship at a Baptists church every week, just as I do not worship at temple every Saturday. However, there is no reason why I would not go back for those special occasions that are important to my family and friends. In the case of Baptists, they don’t have marked high holy days as do Catholics and Jews. But I know that they have weddings, baptisms, funerals and special events.
From the law of the Catholic Church, once you become a Catholic, it is wrong to REGULARLY worship at any other church or temple, because you are disrespecting those people. It is wrong to go to Communion Service with them. Gong to the Baptist service every week is for the Baptist Christian, not the Catholic Christian. For a Catholic to do so, knowing that he is not a Baptist and has no interest in being a Baptist is offensive to the Baptists. Why would I want to pretend to be one of them? Their faith is not a game to them. Pretending is a form of play. We don’t play with people’s belief systems.
Attending a Baptist church for a special event is a sign of unity. You are united by the event and by charity. If you go to a Baptist church for a wedding, you are there because of the wedding. You are doing the loving thing to support two people who are validly getting married. If you go for a funeral service, you are united to them in their sorrow and in the hope of the resurrection. One need not be Baptist to be united to them in these situations.
The Holy Father is saying that it is OK to keep what is good from the Baptist, even though you’re a Catholic and it’s also necessary to maintain your fraternal relationships, because we are brothers and sisters. Continue to love the people and everything they gave you. He’s not saying, “Become a Catholic and pretend to be a Baptist by going to Baptist service every Sunday.”
Conclusion, if the grace of God is pulling you toward Catholicism, you have a duty to God to follow that grace to its logical conclusion. That means that you become a Catholic and cease to be a Baptist. But you do not break with all the good things that you received through them or with those good friendships, nor do you never set foot there again for special occasions. They’re not demons. They are your brothers and sisters. The young girl can continue to be your friend. You will also meet young people at the Catholic Church and make friends there. Eventually, you can even have everyone together for a birthday party, a trip to a movie, a basketball game, whatever it is that you young people do today . . .THE GOOD THINGS THAT YOU DO.
Fraternally,
Br. JR, OSF