Here we see exactly why the Lord elected some and not others:
"But we are bound to give thanks alway to God for you, brethren beloved of the Lord, because God hath from the beginning chosen you to salvation through sanctification of the Spirit and belief of the truth" (2 Thess.2:13).
AGAIN, you cherry pick verses right OUT of context. First of all the verse you quote says NOTHING about election and secondly if you read a little further you will see in v15, that Paul instructs them to "stand firm and hold fast", which is not something one would say if they held to your doctrine POV, as I assume you are Calvinist by this thread?
The elected ARE Christians...and it is a title you obviously don't understand.