“Hear, O Israel: Today you are on the verge of battle with your enemies; do not be afraid…for the LORD your God is He who goes with you, to fight for you against your enemies, to save you.” (Deuteronomy 20:3-4)
Before they entered the promised land Israel was told they would have to do battle with their enemies, but not to fear for the LORD would “save” them…and He did.
Today we are told that the struggle of humanity is with another kind of enemy - "spiritual forces"…
“For our struggle is not against flesh and blood, but against the rulers, against the powers, against the world forces of this darkness, against the spiritual forces of wickedness in the heavenly places.” (Ephesians 6:12)
Again, the Lord has overcome these "world forces of darkness". Humanity does not have to fear the various tribulations we encounter if we simply believe the "word of God".
“In the world you have tribulation, fear not for I have overcome the world." (John 16:3)
"...put on the full armor of God…take up the shield of faith…take up the helmet of salvation and the sword of the Spirit, which is the word of God." (Ephesians 6:13, 16,-17)
It is a trustworthy statement deserving full acceptance. For it is for this we labor and strive, because we have fixed our hope on the living God, who is the Savior of all humanity…” (1 Timothy 4:9-10)
Humanity can only "take up" the shield of faith and the helmet of salvation when they hear about it and trust that it is a free gift from God. Trusting calms our fears.
"For it is by grace you have been saved, through faith—and this is not from yourselves, it is the gift of God— not by works, so that no one can boast." (Ephesians 2:8-9)
"God has not given us a spirit of fear..." (2 Timothy 1:6)