Feast of the Holy Trinity; Proof That Solo Scriptura Fails

Today the Church celebrates the great solemnity of the Holy Trinity, always celebrated one week after Pentecost. Why does the Church need to write an office and liturgy to highlight the doctrine of the Triune God?  Because at one time in the history of the Christian faith, almost half of believers didn't understand the true nature of God the Father, Jesus the Son and the Holy Spirit, the third person of the Trinity.  Our Church Fathers provided us with a Creed, a white paper, so to speak, on what it is we believe about God.
   Why was this necessary if the Bible is perpiscuous (self -elaborating) If all we need to know about the nature of God is clearly elucidated in Holy Scripture, why did Arius and his heretic bishops and followers argue that Jesus wasn't truly God?  Why do Jehovah's Witnesses and similar cults today publish a pamphlet that gives 200 "Biblical Proofs" that Jesus is not God?  The answer is that the concept of using the Bible Alone(Solo Scriptura) without the Church Jesus started will lead to error, confusion and ultimately schism. The extremely large number of Protestant denominations which grows by the day is empiric proof of this epic failure.
 

 Saint Vincent of Lérins of the early fifth century concurs, "Therefore, it is very necessary, on account of so great intricacies of such various error, that the rule for the right understanding of the prophets and apostles should be framed in accordance with the standard of Ecclesiastical and Catholic interpretation."

Don't misunderstand this post as somehow denigrating Scripture, for we believe it is the Divine Word of God, but Christ also gave us His Church through which the third person of the Trinity, the Paraclete is promised to lead us in all truth. This feast day reminds me of that.