Believing in vain

 ICo.15:1-2 "Moreover, brethren, I declare unto you the gospel which I preached unto you, which also ye have received, and wherein ye stand; by which also ye are saved, if ye keep in memory what I preached unto you, unless ye have believed in vain." It is question to either keep the Gospel as it was originally proclaimed, or believe in vain.

Enemy of the faith

Ezr.4:1-3 "Now when the adversaries of Judah and Benjamin heard that the children of the captivity builded the temple unto the LORD God of Israel;