If the Church apostatized in the First Century, then why they're using the Bible that was ratified by the same Church in the Fourth Century?

"...if the Church did commit apostasy in the first centuries, then why does the Iglesia ni Cristo use the Holy Bible that was ratified by the same Church in the 4th century?"

A PRIMER ON THE BELIEFS OF THE IGLESIA NI KRISTO
PART TWO, Section I, Item No. 7

The Holy Bible ratified by the Catholic Church in the 4th Century during the time when the Church already "apostatized" (Source: CatholicSay)