In Philippians 4:7 we have a wonderful promise: “The peace of God, which passes all understanding, will guard your hearts and your minds in Christ Jesus.” It is important to note the context of this promise, because that’s where we find the condition: “Do not be anxious about anything, but in every situation, by prayer and petition, with thanksgiving, present your requests to God” (verse 6). God’s peace is promised to guard those who pray—with thanksgiving—about everything. This peace will transcend our ability to understand it.
Deuteronomy 20:4 (NIV)
For the Lord your God is the One who goes with you to fight for you against your enemies to give you victory.