2 Corinthians 6 :7 (NLT)
We faithfully preach the truth. God’s power is working in us. We use the weapons of righteousness in the right hand for attack and the left hand for defense.
In the similar vein, if we are confident in our salvation, this becomes our weapon too.
Ephesians 6:13-15 (NLT)
13 Therefore, put on every piece of God’s armor so you will be able to resist the enemy in the time of evil. Then after the battle you will still be standing firm. 14 Stand your ground, putting on the belt of truth and the body armor of God’s righteousness. 15 For shoes, put on the peace that comes from the Good News so that you will be fully prepared.[d] 16 In addition to all of these, hold up the shield of faith to stop the fiery arrows of the devil.[e] 17 Put on salvation as your helmet, and take the sword of the Spirit, which is the word of God. Stand your ground, putting on the belt of truth and the body armor of God’s righteousness.
1 Thess 5:8 (NLT)
But let us who live in the light be clearheaded, protected by the armor of faith and love, and wearing as our helmet the confidence of our salvation.
1 Thess 5:8 encourages us who live in the light to be clearheaded. If we are unsure of our righteousness in Him and our salvation then we will try to attain them using our own strength. This puts us on a dangerous path of self righteousness and self salvation projects.
We are familiar with the bible verse that says our righteous deeds are like filthy rags. Let us investigate further :
We are all infected and impure with sin. When we display our righteous deeds, they are nothing but filthy rags. Like autumn leaves, we wither and fall, and our sins sweep us away like the wind.
Now what are those filthy rags?
The Hebrew is וכבגד עדים (ukabeged ehdim, literally, "and like as rags of menstruation"). The words come from these roots: בגד (begged, rags, cloth, etc.) and עד ('ehd, menstruation or menstrual flow)[ http://www.bibleword.org/rags2.shtml#a]. It is menstrual cloth. It is unclean [Leviticus 15:19-33].
What do we do with the filthy rags?
Isaiah 30:22 [NIV 2008]
...Then you will defile your idols overlaid with silver and your images covered with gold; you will throw them away like a menstrual cloth and say to them, "Away with you!"
If we do not believe we are righteous in Him, then what it means is that we are piling up all these filthy rags and telling God : 'Here you are, you can have them and now make me righteous.' Yucky!
The goodnews is that Jesus has done it all. Our right standing withHim (righteousness) and salvation come in a package as a free gift from God when we identify with Him in His death and ressurrection. We cannot earn righteousness or salvation. We receive them with thanksgiving. Only believe "It is finished".