Church is not a requirment in order to be saved. The only way that you can be saved is to believe that Christ is the one true way, God's incarnated Son, who came to the Earth to destroy death and bring peace to all those who trust in Him.
Going to church, on the other hand, will be a very large opportunity for you to grow in your walk with Christ through the knowledge of others and their experiences. That's why God blesses pastors to help teach and help the walks of people.
the best ones are the small churches that have less then 100 people attending the service
This is not true at all. Any church can be "good" as long as they stay on line with the Scriptures and is full of the Holy Spirit. I went to a church with a weekly attendence of about 3,500, and had over 10,000 members of the church. The main Sactuary sat 2,500, and the Fellowship Hall was the size of a football field (indoor) and sat 1,500 WITH tables. 2,500 without. It had 4 survices on Sunday. The church has the 63rd largest pipe organ in the world. 7, 667 Pipes, with a 5 keyboard player, and 265 stops.
This church, through God, has done many great things. It's called Coral Ridge Presbyterian Church, located in Ft. Lauderdale, FL. The senior pastor, Dr. D. James Kennedy Ph. D, is the chairman and president of Coral Ridge Ministries, a multi-million dollar ministry. He is also the founder of Evangelism Explosion (EE). The church currently has at least 1 missionary in
every single country in the world, the first ministry to do so...ever.
The youth group had about 500 kids (grades 6-12) with an attendence on sunday of about 200. The other grades were twice that size.
What is my point of all this? It may come off as "bragging," but no. I'm doing this to prove a point to you that church large or small, many members or only a few meeting in homes, has the potential to be the greatest as long as they are full of the Holy Spirit, and stay on track with the Scriptures.