Well, firstly, I quoted 3 sources earlier. Any thoughts on that? First, 2 Macc 12:46, written before the NT. When the Canon of the Bible was determined in the 4th Century, using Church Tradition, these books, 1 and 2 Maccabees, were included in it. Luther took it out, after more than 1000 years of it being in the Canon, because he could not explain why it taught Purgatory. But purgatory is also taught in the NT in 1 Cor 3:13-15; it says some Christians are rewarded for their good works done in faith, while other Christians are not, but suffer loss and are saved only through fire. Finally, from the earliest ages after Christ and His Apostle, as is historically demonstrable, the Christian Church prayed for the departed, which shows a belief in purgatory.
Where is Tradition preserved? (1) in the writings of the Church Fathers, some of whom were direct disciples of the Apostles. (2) in the liturgies of the Churches, e.g. the Church of Jerusalem (of which St. James, who wrote the Epistle we have in the Bible, was first Bishop) has the Liturgy of St. James:
https://en.wikipedia.org/wiki/Liturgy_of_Saint_James and finally (3) in the Ecumenical Councils. As I said, most churches, including Anglican, Lutheran Churches etc profess the Nicene Creed.
Take another example? Should Churches baptize infants? Tradition says yes. Origen wrote:
"The Church received from the apostles the tradition of giving baptism even to infants. The apostles, to whom were committed the secrets of the divine sacraments, knew there are in everyone innate strains of [original] sin, which must be washed away through water and the Spirit." https://heidelblog.net/2020/05/orig...practice-of-infant-baptism-from-the-apostles/ Catholic/ Orthodox and Anglican/Methodist Churches do this, and Martin Luther agreed on this point.
But based on Luther's own principles, including Sola Scriptura, the Anabaptists first rejected the practice in the 16th century, something unheard of in 1500 years before that, in either East or West. And Luther could not answer/refute them.
Actually, the answer is simple: If Luther had consulted the Church Fathers, he would have found the answer. Tradition agrees with Scripture. There's no question of Tradition contradicting Scripture. It just makes a doctrine implicitly contained in Scripture more explicit, as the Nicene Creed does for the Biblical doctrine of the Holy Trinity. So, is there Biblical Evidence for Baby/Infant Baptism? Yes. (1) On Pentecost, St. Peter says in Acts 2 the promise of Baptism and the Spirit is for you and for your children, showing no one is excluded:
"38 Peter replied, “Repent and be baptized, every one of you, in the name of Jesus Christ for the forgiveness of your sins. And you will receive the gift of the Holy Spirit. 39 The promise is for you and your children and for all who are far off—for all whom the Lord our God will call.”
(2) Second, the Apostles baptized whole households:
"At that hour of the night the jailer took them and washed their wounds; then immediately he and all his household were baptized." (Acts 16:33)
Again, it shows no one was excluded. Baptism has replaced Circumcision, as Col 2:11 indicates. Circumcision was given even to infants. And so Baptism also is. In fact, so widely known was this in the Early Church that some claimed Baptism must be given on the 8th day after Birth only, as Circumcision was.
There are other pieces of Biblical Evidence too, but these will suffice for now. What I'm saying is studying the history of the Tradition of the Early Church makes it easier - Origen says the Church received from the Apostles the Tradition of baptizing infants. That shows Infant Baptism is of Apostolic Origin.
And so, Apostolic Tradition, from the Early Church, is useful in settling the question of what the Apostles handed down. St. Paul the Apostle tells the Churches to hold fast to that Tradition the Apostles handed on.
God Bless.