Now that’s really funny … since the RCC is the self-imposed “authority” on what God would and wouldn’t have done or said!
The Catholic Church is not a self-imposed authority. The authority of the Church comes from Jesus Christ Himself. “And I say to thee: That thou art Peter; and upon this rock I will build my church, and the gates of hell shall not prevail against it. And I will give to thee the keys of the kingdom of heaven. And whatsoever thou shalt bind upon earth, it shall be bound also in heaven: and whatsoever thou shalt loose upon earth, it shall be loosed also in heaven” (Matthew 16:18-19)
Christ gave Peter, first among the Apostles and the first Bishop of Rome, the keys to the kingdom of heaven and the authority to bind and loose. So, the Church’s authority is far from “self-imposed.” It is from Jesus Christ Himself.
All that we know of God is spelled out in scripture and all that God wants us to know as pertains to our salvation is contained within the pages of scripture.
If this were true, since the doctrine of sola scriptura is not in scripture, it must not pertain to our salvation. (This is true, it is a false, heretical doctrine designed to weaken the One, Holy, Catholic, and Apostolic Church).
More importantly, all we know of God is not spelled out in scripture. God sent His only son to us in the flesh that me may know Him. “And the Word was made flesh, and dwelt among us: and we saw his glory, the glory as of the only begotten of the Father, full of grace and truth.” (John 1:14) (Mary is also described as “full of grace” - interesting)
Jesus is the living Word of God. And everything he did and taught is not recorded in the Bible. “But there are also many other things which Jesus did, which if they were written every one, the world itself, I think, would not be able to conatin the books that should be written.” (John 21:25)
So are the things Jesus did and taught lost to us? No. Jesus said, “But the Paraclete, the Holy Ghost, whom the Father will send in my name, he will teach you all things, and bring all things to your mind, whatsoever I shall have said to you.” (John 14:24) The Holy Spirit will bring to remembrance the things that Jesus said and did that are not recorded in the Gospels. Jesus tells his disciples gathered in the upper room, “I have yet many things to say to you: but you cannot bear them now. But when he, the Spirit of truth, is come, he will teach you all truth: for he shall not speak of himself, but what things soever he shall hear, he shall speak: and the things that are to come, he will show you. He shall glorify me: because he shall receive of mine, and will declare it to you.” (John 16:12-14)
The Holy Spirit will come to the Apostles, and their successors the Bishops of the Church, and teach them all truth. This is what Jesus promised. He did not say that all truth will be revealed in the Bible. He promised that he would lead the Church into all truth and bring to remembrance all that He taught and did. Jesus, the Son of God, is the revealed Word of God and He contains all that is necessary for our salvation. Jesus didn’t write a book - he founded a Church, the Catholic Church, and promised to send the Holy Spirit to guide that Church into all truth.
Mary’s assumption and her immaculate conception is not God’s inspired word and only serves to place Mary on level she neither deserves nor wants.
When the Angel Gabriel addresses Mary, he says to her, “Hail, full of grace, the Lord is with thee: Blessed art thou among women.” (Luke 1:28)
Mary’s Immaculate Conception can be inferred from these words. She is “full of grace.” There is no room for sin with her. Also, the Church, led into all truth under the influence of the Holy Spirit as promised by Jesus Christ, has infallibly declared that Mary was immaculately conceived and that she was assumed bodily into heaven.
Catholics have not been misled by the man-made, false doctrine of sola scriptura, so we are not under the illusion that all truth is contained in the Bible. We believe in the promises of Jesus Christ, that he will send the Holy Spirit to guide the Church into all truth and bring to remembrance all that he taught and did. So for Catholics, Mary’s bodily assumption into Heaven doesn’t have to be spelled out explicitly in the Bible for it to be true (it can certainly be inferred from what is in the Bible, and it doesn’t contradict anything in the Bible). It is one of the truths that the Holy Spirit has led the Church to and brought to remembrance.