Now may the God of peace himself sanctify you completely, and may your whole spirit and soul and body be kept blameless at the coming of our Lord Jesus Christ. He who calls you is faithful; he will surely do it. - 1 Thessalonians 5:23-24
Armor of God
... take the helmet of salvation, - Ephesians 6:17
... and for a helmet the hope of salvation. - 1 Thessalonians 5:8
What is the salvation process?
God chose the church of the Thessalonians as the firstfruits to be saved, through sanctification by the Spirit and belief in the truth. To this, he called them through the gospel, so that they may obtain the glory of our Lord Jesus Christ. (2 Thessalonians 2:13-15)
How do I know someone is saved?
Paul knows God chose the people of the church of the Thessalonians through their works and reception of the gospel. They did not merely hear the gospel, they submitted to the power of the Holy Spirit as He convinced their consciences and amended their lives. (Matthew Henry's Commentary on the Whole Bible: Complete and Unabridged by Hendrickson Publishers, Inc, 2003. Page 2338)
We give thanks to God always for all of you, constantly mentioning you in our prayers, remembering before our God and Father your work of faith and labor of love and steadfastness of hope in our Lord Jesus Christ. For we know, brothers loved by God, that he has chosen you, because our gospel came to you not only in word, but also in power and in the Holy Spirit and with full conviction. (1 Thessalonians 1:2-5)
How do I know someone is not saved?
Those who are perishing refuse to love the truth and so be saved. They do not believe the truth but have pleasure in unrighteousness. (2 Thessalonians 2:10-12)