“Christ loved the church and gave himself for it” (Ephesians 5.25).
The first thing a one who has been saved should do is to be baptized by immersion in water into a local, autonomous, New Testament Church whose main goal is the glory of God and uplifts the name of Jesus Christ and His name only. The local church was ordained by God to do his work in this age of grace. All ministries should be out of a properly ordered New Testament church body which is under the authority of the Lord Jesus Christ and Him alone. A church which is a legal entity (a non-profit corporation, unincorporated association, business trust, charitable trust, a 501(c)(3) or 508 tax exempt religious organization, etc. is not under Christ and Him alone).
Matthew 16:18 “And I say also unto thee, That thou art Peter, and upon this rock I will build my church; and the gates of hell shall not prevail against it.”
Ephesians 1:22: “And hath put all things under his feet, and gave him to be the head over all things to the church.”
Colossians 1:18: “And he is the head of the body, the church: who is the beginning, the firstborn from the dead; that in all things he might have the preeminence.”
The New Testament gives complete instructions for the order of a New Testament church. Every church member-pastor, teacher, evangelist, elder, deacon, etc.–although given a specific role in the spiritual body which is a church–is equal to all other members and is to be guided by New Testament commandments and principles so that “the whole body fitly joined together and compacted by that which every joint supplieth, according to the effectual working in the measure of every part, maketh increase of the body unto the edifying of itself in love” (Ep. 4.16).
Simply Church 
So, how does one go about finding out which churches in his/her area is under the 501(c)3 or 508 thing so we know which ones we can be safely baptised into?
And if the one we already go to and have gotten attached to the people at is under it, what should we do about it?
Very good questions. Most churches in America are heretical or apostate. It is hard to find a church who is trying to please our Lord in all things. Most pastors never really study and apply the Bible doctrine of the church. Feel free to e-mail me at jerald.finney@sbcglobal.net or call me at 512-785-8445. I have moved twice in the last three years in search of such a church. First move was over 1000 miles. Second move was almost 1000 miles. I love the church I am now a member of; and, Lord willing, will be here the rest of my life. Each time I moved, I had to leave people I loved dearly. I moved because I will put Christ above father, mother, relatives, and friends, pastors, and anyone else. To God be the Glory, the honor, the praise, the obedience!