The Church suppressed a fifth ‘lost gospel’—the Gospel of Thomas—because it
contradicted Church teaching.
I would say that is a true statement said in a misleading way. Many letters, gospels and books were written about the life, passion and death of Jesus, only a few met the criteria to be included in the canon of Scripture. Many of those do not necessarily contradict Sacred Scripture or Church teaching, but were not included in the canon because they lacked something such as maybe universality. Some letters such as Pope St. Clement’s letter to the Corinthians were considered acceptable for teaching early on, but later, again for lack of meeting all criteria were omitted, or “suppressed”. This does not suggest the Church did anything suspect, or nefarious in compiling the canon, but quite the opposite shows the Church seeking clarity, orthodoxy, truth and universality in the canon. There are plenty of sermons and letters from Church fathers in the 1st century we can read, learn from and bolster our faith with that did not make it into Scripture as well. The Didache is a document the early Church used to impart orthodoxy and clarity on the teachings of Jesus Christ (the name “didache” means teaching) - sort of the first Catechism, yet it too is not part of the canon.
When it comes to the gnostic gospels such as the gospel of Thomas, the gospel of Philip, Mary Magdaline, Pontius Pilate and so on, those were rejected from the canon because they lacked truth, historical accuracy and consistency with Christian teaching from the Apostles.
