When an atheist challenges me to prove God's existence, I point them to Jesus. This is often met with silence. Further questions opens the way for me to speak about Christ, His teachings, His miracles, His death and Resurrection.
Eastern Orthodoxy is also catholic in the historical sense of the word, describing the fullness of the Body of Christ as confessed in the Nicene Creed. So, it is entirely accurate to refer those under the See of Rome specifically as the Roman Catholic Church.
There is no such thing as Roman Catholics. The proper name is the Catholic Church. That’s the name used in its official documents, including the Catechism and Code of Canon Law.
The leaves that do not fall naturally from the tree will eventually be taken by the rain before winter or by the weight of snow. Even the most tenacious leaves must eventually fall.