"Soul songs" usually refer to Christian hymns, which are usually used to praise God and pray for peace and happiness. In the Lord, we get real peace and happiness, because our confidence comes from God's grace and love. God has given us life, strength and wisdom, so that we can face the challenges and difficulties in life. At the same time, God also gave us love and care, which made us feel the warmth and care between people.
Therefore, "30 spiritual songs praising the true peace in the Lord" means that we have achieved real peace and happiness in the Lord, which is one of the most precious treasures in our lives.