They can't teach it. They've painted themselves into a corner. How can you claim to have all kinds of special powers and authority if the simple Truth is believe The Gospel and you are saved. Things such as the treasury of merit, indulgences, purgatory, and works such as giving their church money become meaningless.
Instead what has happened is they teach dependence on them (the church). The church becomes the conduit of their salvation. As a result defense of their church becomes the same as defending their faith.
God willing, they will seek the answer elsewhere.
We know God is sovereign and God will have all He intends to have. Those that God wants at some point after hearing the question "what is The Gospel" will seek the answer. Those that want pats on the back for being faithful to their church will find out how serious their error is at the White Throne Judgment.
Fortunately, they still have the scriptures which contains the saving Gospel. God can still witness to those who have ears to listen.
And there you have it in a nutshell. Jesus becomes a window dressing at that point; something to give legitimacy to the system of works they have established to replace the Law that God gave.
No system of works, rules, regulations, and ceremonies man sets up in it's place is going to save if the Law God Himself gave doesn't.
AMEN!
Every star named; every hair numbered. Every sheep of Christ's flock brought safely home.
For both he that sanctifieth and they who are sanctified are all of one: for which cause he is not ashamed to call them brethren, Saying, I will declare thy name unto my brethren, in the midst of the church will I sing praise unto thee. And again, I will put my trust in Him. And again, Behold I and the children which God hath given me." -- Hebrews 2:10-13"For it became him, for whom are all things, and by whom are all things, in bringing many sons unto glory, to make the captain of their salvation perfect through sufferings.