Let me explain, since people are busily downvoting you.

Christ changed it all. His argument was that gentiles can be God's children, and made a point in finding 'sinners' to convert. (illness was considered God's work, so if one, for example, laid hands on someone and prayed, then one was considered to be interfering with God's work. And anyway, tax colletors and prostitutes were definitely not acceptable to attend prayer meetings.

So, for your Korean example: I would definitely consider a convert as a true Christian, because Christ said anyone can worship God.

Some people are still butthurt about that, because the doctrine was exeptional - as in, only those with the correct bloodlines was accepted in the club. How dared he?