A Catholic would probably know or learn about the veneration of the martyrs as mentioned above…about the definition in the first three centuries of the concept of communion of saints - including the Church Militant (us), the Church Penitent (the holy souls in purgatory), and the Church Triumphant (the souls in heaven). And this is all very, very ancient and part of true Christian doctrine.
Also, it’s quite interesting that f.e.x they speak of something as not being biblical, while their own Bible is not biblical :shrug: Ex. does it include 2 Maccabees? Surely not, since it has been under the hatred of heretics, particularly that of Luther who “wished it had not come to us at all”. Anyways, this book of the Sacred Scriptures (infallibly accepted as such by several Councils of Holy Church) has a very interesting quote at 15:11-17
When he had armed each of them, not so much with the security of shield and spear as with the encouragement of noble words, he cheered them all by relating a dream, a kind of waking vision, worthy of belief.
What he saw was this: Onias, the former high priest, a noble and good man, modest in bearing, gentle in manner, distinguished in speech, and trained from childhood in all that belongs to excellence, was praying with outstretched arms for the whole Jewish community.
Then in the same way another man appeared, distinguished by his white hair and dignity, and with an air of wondrous and majestic authority.
Onias then said of him, “This is a man who loves his fellow Jews and fervently prays for the people and the holy city—the prophet of God, Jeremiah.”
Stretching out his right hand, Jeremiah presented a gold sword to Judas. As he gave it to him he said, “Accept this holy sword as a gift from God; with it you shall shatter your adversaries.”
Encouraged by Judas’ words, so noble and capable of instilling valor and stirring young hearts to courage, they determined not merely to march, but to charge gallantly and decide the issue by hand-to-hand combat with the utmost courage, since city, sanctuary and temple were in danger.
So here we find two saints, a former High Priest and the prophet Jeremiah, both interceding for the people before God (though, of course, we know they were in the place of the patriarchs or limbus patrum awaiting the coming of Christ, and not yet in heaven). And that’s in the Bible - though of course, to keep up with the sola scriptura heresy, the pages of this book had to be teared away from the Sacred Scripture.
And there’s much more to be learned on the cult of dulia or veneration that Holy Church tributes to the saints, who are members of the body of Christ.
But even if a Catholic was able to answer very well, these teachings can hardly be accepted or understood without a humble heart and acceptance of Sacred Tradition and of the fullness of Sacred Scripture.