"Then Solomon stood before the altar of the LORD in the presence of all the assembly of Israel and spread out his hands toward heaven, and said, "O LORD, God of Israel, there is no God like you, in heaven above or on earth beneath, keeping covenant and showing steadfast love to your servants who walk before you with all their heart, who have kept with your servant David my father what you declared to him. You spoke with your mouth, and with your hand have fulfilled it this day. Now therefore, O LORD, God of Israel, keep for your servant David my father what you have promised him, saying, 'You shall not lack a man to sit before me on the throne of Israel, if only your sons pay close attention to their way, to walk before me as you have walked before me.' Now therefore, O God of Israel, let your word be confirmed, which you have spoken to your servant David my father. But will God indeed dwell on the earth? Behold, heaven and the highest heaven cannot contain you; how much less this house that I have built! Yet have regard to the prayer of your servant and to his plea, O LORD my God, listening to the cry and to the prayer that your servant prays before you this day, that your eyes may be open night and day toward this house, the place of which you have said, 'My name shall be there,' that you may listen to the prayer that your servant offers toward this place. And listen to the plea of your servant and of your people Israel, when they pray toward this place. And listen in heaven your dwelling place, and when you hear, forgive." (1 Kings 8:22-30)
When God calls us to worship Him, His people respond with a prayer to invoke the presence of the Lord. While God is omnipresent, He has times and places where He is present in a special way. Thus we summon this special presence of the Lord in our worship, our new and redeemed hearts agreeing with our Lord's Call to worship in His presence.
What an awesome privilege it is to approach the throne of grace! It is not something to be taken lightly and casually. Proper Biblical worship is honoring to God, and irreverent worship displeases Him. For the redeemed, there is joy in the presence of the Lord, but we are also told to "Serve the LORD with fear, and rejoice with trembling." (Psalm 2:11). It sounds strange for someone to "rejoice with trembling", but that is what a redeemed sinner does in the presence of a holy God.
Invoking the presence of the Lord is a serious matter indeed, and one who is truly aware of God's nature, and his own, cannot but be in awe. Even as those who are predestined to adoption, God should scare us. He is too big. We are too small. He is too Holy, and we are too wicked. The idea that we could approach him in a careless, irreverent manner is unthinkable to the sober man.
"The LORD reigns; let the peoples tremble! He sits enthroned upon the cherubim; let the earth quake!" (Psalm 99:1)
When we hear the universal call to worship each sabbath, let us respond in agreement with our Lord with a prayer of invocation, doing so soberly as we prepare to meet the true and living God, ready to beseech Him to "listen in heaven your dwelling place, and when you hear, forgive".
Recommended Reading: With Reverence and Awe: Returning to the Basics of Reformed Worship by Hart and Muether