Yes I’ve heard this same argument…and it’s very convenient for them…BUT…when you really start to probe the reality of this “sound bite”, the argument does not stand up.
The Eucharist is a perfect example. Jesus Clearly states in Holy Scripture that if you do not eat His body and drink His blood you have no life in you. This makes this entire passage of great import to salvation…yet do ALL agree on what this means? they do not. Some protestants hold to “real presence” and some to “symbolic presence”.
Baptism is another example. Scripture says we must repent and be baptized…water and spirit…yet there are protestants who reject the necessity of water baptism…
The ability to lose salvation after baptism is another. Some protestants believe you can, others believe you cannot. This is of critical import to how one might choose to live their life.
The NT is filled with exhortations to unity…unity so tight that we become one with Christ and with the father. (John 17:20-21). Paul and Peter exhort that we be of one mind and have no dissensions…Authority is granted to a visible Church in Mt 18:15-18 and that authority is exercised over the universal Church at the Council of Jerusalem in Acts 15…Yet your protestant friends will try to say that Mt 18 refers only to the “Local Church community”…Which is laughable when, a) it does not say this anywhere in Scripture and b) different local protestant communities,
even in the same city come to different beliefs and firmly refuse to use the
biblical model for resolving these serious differences…
No - the argument that they agree on essentials just doesn’t hold up…Get a big enough group of protestants together and they won’t even be able to agree on what the essentials ARE. Well - there will be one or two. That 1) Jesus is God and rose from the dead…and 2) the Catholic Church is wrong…

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I’ve been on the same journey as you. I am happy to help.
May you be blessed greatly during this Christmas season.
Peace
James