The idea of an invisible Church (via BOD, invisible ignorance, implicit Faith, etc) is condemned by Christ Himself. The Catholic religion is visible and tangible and is concerned with the externals, which Christ Himself emphasized. He is not only spirit, He is body too. That is what we do with the Sacraments and Holy Eucharist! We need to be visible members of His Body in order to be saved.
Why are you troubled, and why do thoughts arise in your hearts> See My hands....handle and see, for a spirit, hath not flesh and bones, as you see Me to have (Luke 24:38)
Popes have also condemned this heretical notion that one can be part of the Church invisibly (again, via last minute BOD, invisible ignorance, implicit faith, etc).
The Church is visible because she has a body. Therefore they are straying from divine truth who imagine the Church to be something which can neither be touched or seen, something merely "spiritual" as they say, a Churh in which many Christian communities, although separated from one another by faith, could be joined by some kind of bond invisible to the senses, How griveoulsy are they mistaken who have imagined a hidden and invisible Church according to their own devices!
Pope Pius XII
Those who arbitrary conjure up and picture to themselves a hidden and invisible Church are in griveous and pernicious error.
Pope Leo XIII