Years ago, the Protestant evangelical in me received a helpful jolt, at least in respect of thinking along standard "anti Catholic" lines, as Protestants/evangelicals tend to do, or at least tended to do back in that day.
The jolt went something like this, Catholicism reads Matthew's Gospel while Protestantism reads Romans and Galatians.
As an evangelical I had to take notice because that explanation involved an appeal to Scripture and not to Tradition. I could see then why Matthew as an apt Scripture in respect of Catholic theology: Matthew present Jesus as the new Moses and his teaching as the new law, with an emphasis on obedience (works done in response to the law), accordingly, and somewhat contrastingly with Romans and Galatians. We might simply mention the last part of yesterday's gospel reading, Matthew 16:17, where Jesus speaks of the return of the Son of Man in judgement,
"then he will repay everyone for what has been done."
It is not that Matthew is a gospel of works-salvation but that Matthew's Gospel proposes a subtle mix of faith-and-works attuned to a Catholic soteriology in a way that a Romans-and-Galatians alone approach is not.
Now let's have a bit of serious fun, if you will. And if you won't, stop reading now!
If Matthew is representative of Roman Catholic theology, then, we might say that Pope Francis' version of it adds in the great Lukan parables on mercy to it (Luke 7:36-50; Luke 10:25-37; Luke 15:11-32). Conservative criticism of Francis (currently focused on his proposed Synod on Synodality) is a doubling-down on Matthew, perhaps especially Matthew 16:13-20.
Protestantism generally and evangelicalism within it is very keen on Romans and Galatians - on the soteriology which emphasises the unmediated by the church but solely mediated by Jesus Christ salvation of God based on the unique sacrifice of Jesus on the cross.
But Protestantism somewhat cheerfully incorporates other books to major on. The Pastoral Epistles are favourites in some circles with the oddity that they say very little if anything about justification by faith and quite a lot about rules for the church. Revelation (and Daniel) are relished by those with eschatological inquisitiveness (and are crucial for Seventh Day Adventist theology). Ephesians plays an important role when predestination is a focus, or, for that matter, spiritual warfare.
By contrast, Pentecostalism is keen on Acts - the dynamic, miracle working Holy Spirit has lots to offer a new expression of the most primitive church in our modern world.
Perhaps a commenter can help me with the Eastern Orthodox church and its "founding scriptures." I suspect John's Gospel is significant.
Obviously we need to get to Anglicanism. Is there a significant Scripture? To the extent to which Anglicanism is reformed and catholic, evangelical and Anglo-Catholic, as well as broad, we could claim "all the above," but I suggest John's Gospel is important to our self-understanding of what kind of church we became in the 16th century and have become across many countries and cultures since.
That is, we have cherished the ability to be a distinctive national church - The Church of England ... of Australia ... Kenya ... Aotearoa, New Zealand and Polynesia, and done so understanding that "the Word became flesh and dwelt among us" means we feel confident that the one church can be differently expressed in the different forms of "flesh" (human life) found around the world.
This thought about Anglicanism is tentative - I would be interested in responses any readers care to make in comments.
The obvious deduction, however, is that all the scriptures cited above are included in the one Holy Scripture! Somehow, in our journey towards Christian unity - towards the healing of the pain of our divisions and towards the completion of our witness to Jesus Christ the Reconciler of the world to God - we need to appreciate that most of our differences are differences which flow from the one authoritative Source - God's Word written!