"… contend earnestly for the faith which was once for all delivered to the saints." Jude 3
One would expect that the most faithful Christian church would use the some form of the name “Church of God.”
Well, the predominant biblical name of the true Church in the New Testament is “Church of God.” Variants of this expression are clearly stated singular and plural forms in twelve different places in the New Testament (Acts 20:28; 1 Corinthians 1:2; 10:32; 11:16,22; 15:9; 2 Corinthians 1:1; Galatians 1:13; 1 Thessalonians 2:14; 2 Thessalonians 1:4; 1 Timothy 3:5,15). The only other singular “church of” statement in scripture is a reference to the “church of the firstborn” (Hebrews 12:23).