For fifteen hundred years, the only christian church officially vested with authenticity was the Catholic Church.
At least, this was THEIR claim.
Authority, so they said, was passed on to them by Jesus himself when he established Peter as "upon THIS rock" (Peter=petra_). Peter was the church's first "father" or Papa=POPE.
Additionally, the entire tradition of teachings from Jesus forward gave them MAGESTERIUM. When official pronouncements were made about faith and morals these teachings were binding on earth and in heaven. Eventually, infallibility was attached.
The various church corruptions and political intrigues cast grave doubt upon the purity of this institution.
Martin Luther, a young monk, challenged the church on their corruptions. This led to debate, expulsion and schism.
PROTESTANTISM needed a source of Authority to rival and surpass Catholicim.
Luther invented SOLA SCRIPTURA.
Instead of church traditions (Magesterium) Luther said the BIBLE ALONE (empowered by holy spirit) was ALL any christian believer needed for TRUTH.
We stand looking back through history at those events, those assertions, those CLAIMS of authority.
NEITHER Catholicism nor PROTESTANT denominational variants have made good on claims of DIRECTION from God, Jesus or Holy Spirit.
How do we know this? "By their fruits you shall know them."
Protestantism engaged in an unending series of bloody wars both against Catholics and against each other. Brother killed brother.
Non-violent sects/cults/denominations have proved to be marginal purveyors of idiosyncratic doctrine and effectiveness.
Jehovah's Witnesses are just one of a long line of schismatic Adventists devoted to novelty, false claims of sole Truth and false prophetic teachings.
The PREMISE that we need a formal building, community or organization of theocrats ruling by decree is a FALSE premise.
Jesus' model of behavior of charity, kindness, goodness, mildness, love and self-sacrifice has to be the shoes a christian walks in WAY BEFORE they get on their high horse and lecture others on CORRECT DOCTRINE!
God, apparently, did NOT safeguard any pure worship, practice or theology beyond showing love, forgiveness and charity.
WHY ISN'T THIS ENOUGH?