The LORD is my light and my salvation; whom should I fear? The LORD is my life’s refuge; of whom should I be afraid?
It is easy to say "the LORD is my light and salvation, whom should I fear" during times of ease. It becomes much more difficult in times of adversity. Nevertheless, it is these times of adversity which increase our faith. St. Pope John Paul II tells us that this verse is spoken in tranquility, in assurance.
This is a psalm of David, probably prior to being anointed the second and third times as the king of Judah and Israel, perhaps while he began fleeing from King Saul. David was an Israelite, probably circumcised on the eighth day, and was taught the laws of God. When he was shepherd of his father's sheep, God had delivered him from the paw of the bear and lion and when the prophet Samuel had anointed him king God afterwards delivered him from the hand of Goliath, so David had tranquility, assurance in the LORD. However, this was only to give him strength to undergo more strenuous hardships in order to teach him to be king.
Let us fast forward to the second David, our Lord Jesus Christ. He was tested because He was the Son of Man. He was tested forty days in the wilderness, and He was delivered from the hands of the religious leaders when they wanted to thrown Him off a cliff. He was delivered also at other times. He had to endure their myriad of verbal assaults. Our Lord had tranquility and assurance in the Father. This was only to give Him the strength to endure His Passion, to make Him perfect through suffering, making Him King.
Our journey began with the Sacrament of Baptism or the grace to grasp the Word, leading to faith and Baptism. Our tranquility and assurance in God increases with each trial we undergo. They are also greatly enhanced through the Sacraments and the liturgy of the Mass, especially the Eucharist. The more involved in these that we become, the more assurance we achieve. We know that we must undergo more and more trials and persecutions. No one escapes them. In the Sacraments and the Mass, we become more enlightened. By means of them also, we become more assured of the fact that He is our salvation, trusting more and more in Him. As a result of the trials and persecutions that He delivers us from, leads us through, and the Sacraments and the Mass, we trust Him as our Refuge. We look not only at our personal trials and persecutions, but upon those of the Catholic Church and how God leads, protects, and delivers her. We must remember that the Catholic Church is the visible Jesus on the earth. When we see that He keeps her, we are also confident that He will keep her members--us as individual members of her.