>>519185280 (OP)
Naturally, you cannot.
Faith in the Word of God is a gift from God.
However, the various different manuscripts of the Bible have no deviation in theology - one would reach the same conclusions about the nature of God and His Will whether you use the Masoretic Text, Septuagint, or Dead Sea Scrolls in combination with any mix of New Testament manuscripts.
This argument was really put to rest with the discovery of the Dead Sea Scrolls, establishing the Bible as the best preserved book of all time, just as God predestined His Word to be.
The grass withers, the flower fades,
But the word of our God stands forever.
— Isaiah 40:8
The reason why people would not believe in the preservation of God's word is always rooted in sin and an unwillingness to repent.
For the wrath of God is revealed from heaven against all ungodliness and unrighteousness of men who suppress the truth in unrighteousness, because that which is known about God is evident within them; for God made it evident to them. For since the creation of the world His invisible attributes, both His eternal power and divine nature, have been clearly seen, being understood through what has been made, so that they are without excuse.
— Romans 1:18-20
And this is the judgment, that the Light has come into the world, and men loved the darkness rather than the Light, for their deeds were evil. For everyone who does evil hates the Light, and does not come to the Light lest his deeds be exposed. But he who practices the truth comes to the Light, so that his deeds may be manifested as having been done by God.”
— John 3:19-21