The Psalms served as the hymnal for the chosen people of God.  Even in the early Protestant churches in Europe, the hymnal was called the "psalter" and it was the psalms, translated in such a way that most of them could be sung to any tune with what is known as Common Meter.

This particular song lays out a simple yet effective mission statement for Christians; give thanks to God - for your life, for blessings, for trials and especially for your faith through which you have access to the forgivness of sins and the covenant of eternal life; call on God's name - be anxious in nothing but in all things, with prayer and petitioning present your requests to God, and the peace which passes all understanding will guard your hearts and your minds in Christ Jesus; make known God's deeds - tell others the good news!  Share with those in your world, especially those who have yet to come to faith in Jesus, all the wonderful things that God has done.

Sometimes, our churches look very good to the outside world; we do good things, we help people, we socialize with one another and we do all kinds of things and find ways to say that it is truly serving God by serving others.  And those are good things.  But few of us are good at giving thanks to God in all things.  We might excell in asking God for things in our prayers as we call on His name, but calling on God's name in the Old Testament also implied worship.  We live in a time when many people will say that they have faith, might even call themselves Christian, but "don't believe in organized religion" so they don't worship.  When it comes to making known God's deeds among those who don't yet know God, most people walk away and call it a day!  That's intimidating, sharing your faith!  But it can be as simple as telling your story; what God has done for you in your life.  How has God made a difference to you?  Why do you serve Jesus?  It's as simple as sharing those two things; no theological treatises, no tough questions to answer, no tricks or slick salesmanship.  Our job is to tell the truth of the Good News, what happens next is God's responsibility!