Psalms 27

1 David had good reason for such trust. God promised that he would be king of Israel. For 20 years David was harassed and endangered, but he had complete confidence that God would protect him and give him the throne.

God provides "light," so we need not fear the "dark." God has saved our spirits from hell, so we need not fear death. At times God may choose to spare our earthly lives, but at some point our physical bodies will have to die.

4 David's requests appear to be spiritual in nature since the Temple was not constructed in David's lifetime. His desires center on being in God's presence and enjoying the beauty, safety, and security that He provides.
6 David was victorious over his enemies during his earthly life, but even more so he would be justified for his faith when God brings him into heaven while his enemies suffer for their disbelief of God. David's response to this hope is to joyfully give (i.e., sacrifice) both physical possessions and songs to God.
7 David earnestly desires to communicate with God.
8 David did not promise with just his mouth, he promised from his heart to seek God. This means he was fully committed in his mind to get closer to God.
9 David recognizes that at times he will sin and he pleads with God not to give up on him and leave.
10 This is probably rhetorical unless it is meant that David's father and mother were unable to provide help for David's most pressing needs at the time. We might be able to recast this to say, "Even if my father and mother give up on me, God will not."
11 Enemies constantly harassed David, but he did not want this to take his focus off of God. He asks God to ease the burden and to save him from his enemies.
13 Most people would be exasperated to the point of despair if they had to deal with the constant physical and verbal attacks of so many enemies like David did. But David places his thoughts on God and can see His goodness despite the evils of this world.
14 When you are discouraged or in danger, remember that God has the final say in all matters. We can trust in His love and justice no matter what our circumstances may be.