I just wanted to know about this. Was it passed on as a part of oral tradition or was it something which the church, under the guidance of the Holy Spirit, understood later, just as it later understood the trinity much better.
Is the dogma (doctrine?) of the Immaculate Conception something that was passed on as Oral Tradition?
The dogma of the Immaculate Conception is implicit in Tradition and Scripture. So it was not passed on from Jesus and the Apostles as an explicit teaching, but it is implicit in all that Tradition and Scripture teaches about the Virgin Mary and her role in the work of Christ.
From the earliest times, Mary was described as never having been subject to sin or under the domination of evil. This implied that she not only avoided sin during her whole lifetime, but also that she was born “saved” before the coming of Jesus, through the anticipated merits of his sacrifice on the cross. But there were discussions as to when exactly she was endowed with sanctifying grace. For example St. Thomas Aquinas, in the 13th century, thought that this happened the moment following her conception, not at her conception. But the view that she was conceived in the state of sanctifying grace became the dominant view and the Feast of the Immaculate Conception was widely celebrated. Then with Ineffabilis Deus, Pius IX made it “official” in 1858.
Reading *Ineffabilis Deus *might help you understand the process that led to the definition of the Immaculate Conception. See newadvent.org/library/docs_pi09id.htm