That’s an argument from Sacred Tradition, though - that the Apostles never wrote about it, and that Christians have never believed this before, and therefore, we should not believe it, even if it seems to us as though the Bible says it - that to determine which Bible is the correctly translated Bible, and which extra-biblical helps are going to be useful to us, we need to look at history to see where the Bible came from, and look at the authors of our extrabiblical helps to ensure that they are following the tradition given to us by the Apostles.
These and all the teachings of the Church are certainly
alluded to and
assumed as true in the Scriptures. If you read the Scriptures while assuming these things are true, you will never have any occasion to wonder whether the writers of Scripture thought they were true - you will read what they wrote, and understand perfectly what they are alluding to, as though they had written it out plainly.
However, there is no statement in the Bible where it says, God is three persons who share one Divine nature and one Divine will, and these three persons are the Father, the Son, and the Holy Trinity. This we deduce by noticing that the Apostles believed in it, and putting together seemingly unrelated Bible verses that, when collated together, show a belief in the Trinity. But if one were not looking for the Trinity, one would not find it - and the proof is that those not looking for the Trinity in Scripture never find it.
There is also no place in Scripture where it says, Jesus of Nazareth is the Incarnation of the Second Person of the Trinity, and has
two natures, 100% Divine, and 100% human. Again, we begin with what the Apostles taught their first followers, and put together groupings of Bible verses, but again, those not looking for Christ’s divine nature in the Scriptures never find it there.
The fact that they interpret the Scripture verses that we see as alluding to these teachings means nothing, since if “the Holy Spirit” is telling them that these verses are referring to something else, the “Bible alone” approach isn’t going to convince them that there are alternative explanations from theirs for the meanings of these verses.
I encounter this sort of thing every day on various fora - not so much here at CAF, but on other fora such as
christian.net and others there are quite a few of them - no one is ever going to convince me that these people don’t exist, because I chat with them via computer nearly every day.