The 3rd Angels message: those who fail to keep the commandments of God and the faith of Jesus receive the mark, page-56

I understand your point about Jesus at the heart of man.
Many false Christs and ant-Christs are recognised by believers.
What makes you think that the knocker in this example is the real Christ rather than a well-published false Christ or anti-Christ?
Should we not be wary of a false Christ or anti-Christ