To the person who has received a Spiritual revelation - e.g. that Jesus Christ is the Son of God - there is no question because the Spirit Himself reveals it as part of the person's being. It is not like someone else speaking but rather an involuntary speaking within, a compelling not of self-will. (Matt 16, John 1)
Likewise, when one who is indwelled by the Spirit reads Scriptures, the Words come alive within. To someone who does not have yet have this indwelling (or has not yet learned to defer to the Spirit when reading Scripture) - the Bible would be text on paper, a manuscript, interesting literature, etc.
Most important in receiving Spiritual revelations is that God is self-consistent. Each revelation will agree with all of His previous revelations to the believer. Thus if a person believes he has received a revelation which is inconsistent, then there is something desperately wrong. (Cayce, Yates, etc.)
A clear indication that a "revelation" someone claims to have received is not from God is when it disagrees with Scriptures which have already been Spiritually revealed to the hearer as Truth. This is called the Berean test (Acts 17).
Jesus' "a bad tree cannot yield good fruit" (Matt 7) standard is the first test. IOW, if a person claims to have Spiritual discernment and wants to share it with a believer, then the believer should look at the fruits of the speaker’s life (Gal 5) to decide whether or not to listen. “False prophets” would fail this test. Even so, after hearing what is said, many believers will still apply the Berean test.
Personally, I choose not to filter God’s Word through the eyes of mortal men and thus eschew all doctrines and traditions and put everything to the good/bad tree and Berean tests. But that’s just me.
Some are more comfortable relying on the insight of a single spiritual mentor or a lineage of mentors. These have placed their trust in a person or institution between themselves and the Word (Jesus). Certainly, as long as those in between and the ones trusting never lose sight of Christ, there is not so much risked.
However, some will invariably end up worshipping the messenger instead. These are the kind who followed Jim Jones and Marshal Applewhite and David Koresh to their end. And some are led astray into bizarre and destructive behavior.
For that reason, I strongly recommend for all believers to stay focused on Jesus and faithfully apply the good/bad tree test and the Berean test to every spiritual speaker, even the ones they already trust.
My two cents…
That doesn't answer the question at all. It only says that you have chosen a particular side. Others have also had unquestionable spiritual experiences that disagree with yours. Those who've never had such experiences just see two or more people ablsolutely convinced of their beliefs to the point of being willing to die for them.
Comparison of KA Techniques
The figure below presents the various techniques described above and shows the types of knowledge they are mainly aimed at eliciting. The vertical axis on the figure represents the dimension from object knowledge to process knowledge, and the horizontal axis represents the dimension from explicit knowledge to tacit knowledge.