This concept of joy of the Lord comes from Nehemiah 8:10. This point in time in history is when the captives from Babylon were returning to Judea and built the house of God again after King Nebuchadnezzar burnt it down. The Israelites had the book of the law read to them and were saddened.
Nehemiah 8:10 Then he said to them, “Go your way, eat the fat, drink the sweet, and send portions to those for whom nothing is prepared; for this day is holy to our Lord. Do not sorrow, for the joy of the Lord is your strength.”
The joy of the Lord is an amazing strength that you have, but many seem to not use very often. I am referring to times of trouble. When you revert to the joy of the Lord as a response, nothing can work against it. Many seem to forget that joy is a fruit of the spirit and as such, there is no law that can work against it. This actually demolishes the enemy as he doesn’t know how to provoke you when you stay in the joy of the Lord.
Galatians 5:22 But the fruit of the Spirit is love, joy, peace, longsuffering, kindness, goodness, faithfulness, 23 gentleness, self-control. Against such there is no law.
James 1:2 My brethren, count it all joy when you fall into various trials, 3 knowing that the testing of your faith produces patience. 4 But let patience have its perfect work, that you may be perfect and complete, lacking nothing.
1 Peter 1:6 In this you greatly rejoice, though now for a little while, if need be, you have been grieved by various trials, 7 that the genuineness of your faith, being much more precious than gold that perishes, though it is tested by fire, may be found to praise, honor, and glory at the revelation of Jesus Christ, 8 whom having not seen you love. Though now you do not see Him, yet believing, you rejoice with joy inexpressible and full of glory, 9 receiving the end of your faith—the salvation of your souls.
How you respond to circumstance will determine of how you are growing in the spirit, or not growing at all. If you are not growing in the spirit, how then are you putting on the armor of God? To put on the armor, you have to be strong in the Lord and the power of His might. Now do you see how significant joy is, and it’s a source of strength for us. It’s a source of confidence for us that we just don’t believe Jesus is Lord, we know He is.
Ephesians 6:10 Finally, be strong in the Lord and in the strength of His might. 11 Put on the full armor of God, so that you will be able to stand firm against the schemes of the devil.