For David and Judah, going to the temple in Jerusalem was a special thing. There was the house of the Lord. There the people could come before their God and hear His Word. God spoke to them through His preachers, and the people received what they needed to go home and back to their vocations: God's Word of judgment, mercy, and truth.
When the king, priests, merchants, farmers, and even foreigners went into God's house they were blessed by His presence. Their souls were filled by His Word and Spirit. From His Word, the people heard what the Lord did for them every moment of their lives.
The people were gathered by God because it was not good to worship alone. He gathered them to show the unity of faith that the Lord wanted them to share. They shared their faith by preaching, praying, and singing together with the words God gave them to speak. They had one Lord, one Word, and one faith that blessed and encouraged them. This is why the palmist often said, "Let us go into the house of the Lord."
Thanks to Jesus' death and resurrection we don't have to go to Jerusalem to go into the house of the Lord. Now, on account of Jesus, we can go into the house of the Lord at our local church where Jesus promises to be present for us in His Word and gifts of salvation, which His Spirit delivers to us through a preacher.
This way, when we hear the words of blessing pronounced by our pastor, "The Lord bless you and keep you; the Lord make His face shine on you, and be gracious to you; The Lord look upon you with favor and give you peace," we know we have received the same effective word from the same God who blessed David and Judah in the temple. We are given the peace to know that all our sin is forgiven by our gracious God. We enjoy the comfort of knowing that our ways are watched over and protected by the Lord because He has made us a very special people in His kingdom.
As we go to the Lord's house, we remember it is the Lord's house, not our house. The words we hear are the Lord's Word through His preacher, not our words preached by someone we hired to tell us what good people we are and how we're all going to heaven when we die. We are set apart from other people because we are God's chosen people. That's why we go into His house.
We are redeemed by the shed blood of Jesus Christ. We belong to Him now. He blesses us in His house so that we may go back home, back to our vocations, praising Him, glad for the opportunity to have heard His Word, and received His gifts of salvation. And, maybe, as we go about our lives, the Lord leads us to a homeless person, someone who is spiritually homeless, whom He has now chosen to unite with the rest of His people in His house. That's the beauty of God's house. There's always room enough for one more sinner in need of Jesus' blessing.