Don't Orthodox Christians follow man-made traditions instead of the Bible?

The idea that some Christian groups rely on tradition while yours doesn't is completely false. Number one, St Paul says the church is the pillar and ground of truth. Number two, St Paul tells St Timothy to hold on to the traditions handed on to him by his mother and his grandmother. Number three, Protestantism has just as many traditions as Orthodoxy: altar calls, not in the Bible; Sunday school, not in the Bible; praise and worship bands with musical instruments, not in the New Testament, never seen in early Christianity.

The problem is presupposing your own understanding over the historicity of the church. In the first 300 years, churches did not have a complete New Testament; a complete New Testament really doesn't exist until around 330, and even then it's decided by a council of the church. Churches had a gospel and usually the epistle written to them. The people relied on the preaching and the Eucharistic union of participating in the body and blood of Christ.

We know this because we have liturgical texts from the early church that show that is how they worshiped God. Going somewhere to watch a fog machine and somebody dancing on stage, then a 45 minute scholarly lecture, then a donut and a cup of coffee: it's not biblical. But more than that, it's not what the early church was doing.