Jesus Christ went out from Nazareth to preach and teach the Bible promoting humanity and humility. He did not force anyone to follow him but offered himself as the light of salvation to be followed voluntarily.
While walking around the lands he was seen and listened to by many in the open. His disciples were worried about his safety while he was not. Some words of his were spoken in a private setting only for his disciples to hear and understand. The Bible eventually disclosed to all of us what he had said during these encounters. Therefore it can be said that Christianity is an open source of wisdom.
After the crucifixion of Jesus Christ his disciples especially in Italy had to hide underground to protect their lives from persecution. The time came Christianity became the dominant religion in e.g. Europe. A Pope as the immediate representative of the Christian faith was installed. Latest by that time secret organizations of Christian worship had lost their relevance but stood mighty in the open as organizations to explain their ways to worship and do good for humanity.
Their structures and practices were made public secrets no longer kept to hail the light and win over more and more people as Christians to their interpretation of the Bible. Many went down this way and had their coming out but not all saw the need and reasons to stand tall in the open rather than tall in openly secrecy.
In the 21st century with the freedom of religion in many countries especially in Europe hiding in the shadow of the light comforted by the benefits of democracy seem to be the powerful relics of a time gone by. Like it took the Catholic Church 500 years under Pope Johannes Paul II to admit the Earth is not the center of the universe and circles around the sun as Galileo Galileo had declared a shift in these practices might take a few generations more.