The name Christian is an honorable name (Jas. 2:7). This is why Paul persuaded people to be Christians (Ac. 26:28). The church is the bride of Christ (Eph. 5:26-27), and the bride rejoices to honor the name of her husband by wearing His name alone.
Whatever the new testament meant when it was written is still what it means today.
We may see the Word of God through our prejudiced and biased eyes but the truth does not change (Jo. 17:17).
Perhaps the most unpleasant doctrine of the Bible is that of teaching that there is but one body, one church, which God recognizes and accepts. We may wish it were some other way but wishing will not make it so.
We are not inclined to estrange people nor insult them. On the other hand, we do not have the permission to legislate for God. When He has spoken, it must be well with our soul as found in Jer. 38:20, “the voice of the Lord, which I speak unto thee: so it shall be well unto thee, and thy soul”.
There is “but one body” (1 Cor. 12:20). Individuals enter this one body (1 Cor. 12:13) by believing (Jo. 8:24), repenting (Ac. 3:19), confessing (Ac. 8:37) and being immersed (Ac. 8:35-38; Matt. 28:18-20).
Christ is understood to be the savior of the body, the church in Eph. 5:23-25. It is not a matter of getting in the church and consequently Christ will save you, but, when you are saved, Christ adds you to his church (Ac. 2:47).
Obviously, He does not add you to some church instituted by man and governed by human creeds and regulations.