Bismillah: Assalamo Alikum...
The Christians normally preach the message of "LOVE" and "KINDNESS" towards others, not only that, but even to love your enemy however, reading what the apostle John taught in his book will show us something different!!!
"Whosoever transgresseth, and abideth not in the doctrine of Christ, hath not God. He that abideth in the doctrine of Christ, he has <both</i> </b>the Father and the Son. If there come any unto you, and bring not this doctrineRECEIVE HIM NOT INTO YOUR HOUSE, NEITHER BID HIM GOD SPEED: FOR HE THAT BIDDETH HIM GOD SPEED IS PARTAKER OF HIS EVIL DEEDS.
As we can see, according to the Bible (<i>The Christians God's word</i>), It is not allowed for a Christian to welcome Non Christians in their home or to wish them well. and if a Christian wishes well upon the none Christian, then he or she will be sinning. So actually everytime a Christian is greeting you or wishing you well, he or she is sinning according to the Bible.
-Christians cannot welcome none-Christians into their homes
-Christians cannot wish well upon none Christians
-If Christians do wish well upon a none believer they will be sinning