"The Lord is my shepherd; I shall not want."
In this psalm, the speaker describes God as being a "shepherd." This is an interesting comparison, suggesting that God guides his followers and protects them from potential threats, just as a shepherd protects his sheep. This passage contributes to the theme of protection and comfort in this poem.
"He restoreth my soul: he leadeth me in the paths of righteousness for his name's sake."
In addition to being a shepherd, God is also depicted as being a teacher, or advisor. In this passage, the speaker states that God leads his subjects onto the paths of "righteousness," justice and morality. Essentially, if any of God's subjects are straying from the right path, he will nudge and lead them in the right direction, embodying the role of a kind of moral teacher.
"Surely goodness and mercy shall follow me all the days of my life."
The speaker is confident that if he follows the word and direction of God, he will be protected from evil. This offers the reader a feeling of comfort and protection, suggesting that they only need to follow his advice to live a similar life of contentment. Religion often provides a sense of comfort for people, partly because it will often assert the existence of a father-figure or protector, who will ensure faithful people will be protected.