1 Thessalonians

If the only evidence you had of the existence of Christianity were 1 Thessalonians, how would you answer these questions: (1) What is the Christian message? (2) How would you know if someone you met was a Christian?

What is the Gospel message in Thessalonians?

We have been chosen by God to turn away from our sinful lives in order to serve the one true God who sent His Son to rescue us from our sins; His Son died for us, was resurrected from the dead, and is now in heaven and continues to rescue us from the coming wrath.
This answer uses 1 Thessalonians 1:4, and 1:9-10.

How can you tell through Thessalonians who a Christian is? It is through their works of faith originated in the Holy Spirit, the way they toil in their works (or occupations) through the love for Christ, and their patience stemming from the hope in regards to the coming of the New Creation. (1 Thessalonians chapter one, chapter two, and chapter three in succession.)