To understand Tradition, you have to understand that it's simply anything passed down. As such, it can be good, bad, or neutral. The Bible distinguishes between two types of Tradition: Traditions from God, and traditions of men. The former Traditions are absolutely binding. The latter may help or hurt our spiritual journeys: they're good when they help, and bad when they hurt.
Traditions of Men
At two primary points in the Gospel (Matthew 15 and Mark 7, recounting the same event), Jesus condemns the Pharisees' excessive, man-made traditions, which prevented them from being even mildly charitable:
- The Pharisees asked Jesus in Matthew 15:2-3, "'Why do your disciples break the tradition of the elders? They don't wash their hands before they eat!' Jesus replied, 'And why do you break the command of God for the sake of your tradition?'" He explains precisely how they've violated Scripture through their man-made traditions, and concludes in Matthew 15:6, "Thus you nullify the word of God for the sake of your tradition."
- In Mark's parallel account (Mark 7:8-9), Jesus says to the Pharisees, "'You have let go of the commands of God and are holding on to the traditions of men.' And he said to them: 'You have a fine way of setting aside the commands of God in order to observe your own traditions!'" He goes on, in Mark 7:13-15 to say, "'Thus you nullify the word of God by your tradition that you have handed down. And you do many things like that.' Again Jesus called the crowd to him and said, 'Listen to me, everyone, and understand this. Nothing outside a man can make him "unclean" by going into him. Rather, it is what comes out of a man that makes him 'unclean.'" Jesus draws the same conclusion in Matthew 15:10-20.
- St. Paul likewise, warns in Colossians 2:8, "See to it that no one takes you captive through hollow and deceptive philosophy, which depends on human tradition and the basic principles of this world rather than on Christ."
Some Protestants use these verses to argue against the idea of all Tradition. They do no such thing. Each of these verses (as the bolding shows) specifies "human tradition" or "your tradition" as potentially problematic.
Traditions from God
In fact, St. Paul argues explicitly for Tradition when he writes in 2 Thessalonians 2:15, "So then, brothers, stand firm and hold to the traditions we passed on to you, whether by word of mouth or by letter." It's worth noting that the exact same word is used in every one of the passages I've mentioned so far. There are three important things to draw from 2 Thessalonians 2:15:
- Apostolic Tradition is binding.
- Scripture is Apostolic Tradition "by letter."
- Scripture isn't the only Apostolic Tradition.
The reason that Apostolic Tradition, including Scripture, is binding is because it comes from God. Paul refers to Scripture as "God-breathed" (2 Timothy 3:16), so even though it's one of "the traditions [the Apostles] passed on to [us]," Apostolic Tradition doesn't originate from the Apostles, it originates from Christ. For that reason, and for that reason alone, it's binding. If, say, St. Peter happened to personally prefer one type of bread to another for the Eucharist, it's irrelevant. On the other hand, if Christ specified one type of bread (either explicitly or implicitly), we'd be smart to follow Him.
One final note on traditions of men: the ones which Jesus condemned were worthy of condemnation. The one Jesus hones in on is a tradition permitting people to not support their elderly parents if they gave the money to Temple instead. In other words, they were violating a Tradition handed down from God, and replacing it with a tradition handed down from their elders. In no case is that ever okay. But traditions handed down from your elders can be important (and in some cases, binding) helps for your spiritual journey. Likewise, Paul condemns "hollow and deceptive philosophy," not all philosophy. Good philosophy can help to give you a healthy moral outlook, to create a just state, and so on. So there's good, neutral, and bad traditions (and philosophies) of men, and good (and binding) Traditions of God, which we call Apostolic Tradition, because of who handed them on to us.