"All the believers devoted themselves to the apostles' teaching, and to fellowship, and to sharing in meals (including the Lord's Supper), and to prayer." Acts 2:42
I attend a non traditional church. We do not have Sunday School, we have small groups. (Which are starting next month, by the way if you are local.) Some traditional type churches have Sunday School, as well as what I call "mixed" churches. My work church is what I'd consider mixed. They don't have pews or hymn books, they sing both contemporary and hymns, but they do have Sunday School.
In the book of Acts, we see the new believers in Jesus fellow-shipping together regularly. They meet in homes, eat, talk about Jesus, and share what's going on in their lives.
That's exactly what small groups and Sunday School classes do.
Why do we need that in our lives?
We are not meant to live this Christian life alone. We are made for fellowship.
Sharing your life with others is helpful with your walk with God.
Having people you can count on gets you through the hard times.
When the good things happen, you have someone to rejoice with you as well.
First of all, Jesus is the best example. He had 12 friends he was close to, that He poured into their lives, and they helped enrich His.
James 5:16 is a very good example of how others can help in your walk with God. "Therefore confess your sins to each other and pray for each other so that you may be healed. The prayer of a righteous person is powerful and effective." Letting people know what's going on in your life, and them praying for you heals you.
Life is going to throw you some curve balls. Things can happen that are so unexpected, but when you have a small group of people in your life, they help carry the load. Galatians 6:2 is tells us to, "Carry each other's burdens, and in this way you will fulfill the law of Christ."
Romans 12:15 even says it clear as day, "Rejoice with those who rejoice; mourn with those who mourn." When you have folks to rejoice and mourn with you, then you are a blessed person!
Is being in a small group a vulnerable place to be? Yes, it is. But it is so worth it. I remember some of the worst times of my life when my small group of friends helped me deal with life.
Sometimes the prayers of others were the only thing that got me through it all.
What's stopping you from joining a small group or Sunday School class? I promise you, if you try it, you just might find some forever friends that you can do life with. It's worth the risk!