The three gates on each side signify that the Triune God— Father, Son, and Spirit—work together to bring people into the holy city. This is indicated in the three parables in Luke 15 and implied in the Lord’s word in Matthew 28:19. The three parables in Luke 15 concern the shepherd and the lost sheep, the woman and the lost coin, and the father and the returned prodigal son. The shepherd refers to the Son; the father, of course, to the Father; and the woman signifies the Spirit. In order for a sinner to be brought back to the Father’s house, there is the need of the Son, the shepherd, to bring back the lost sheep; there is the need of the Spirit to enlighten the hearts of people that they may repent; and there is the need of the Father to receive the returned and repentant prodigal son. Hence, the Triune God is the entrance into the New Jerusalem.
The fact that the Triune God is working to bring people into the holy city is also implied in the Lord’s word in Matthew 28:19. To be baptized into the Father, the Son, and the Spirit is the entrance into the holy city. Thus, the Father, Son, and Spirit are the three gates on each side of the city. The three gates are not on three sides respectively; rather, there are three gates on each of the four sides repeatedly. The gates on any one of the sides are exactly the same as the gates on the other three sides. This indicates that the Triune God is available to people in all four corners of the earth.
The three gates indicate that the Triune God has come to reach us and to bring us into His eternal economy. The three in the Godhead, the Father, the Son, and the Spirit, have come out in God’s economy to reach us and to bring us back to His economy. A number of verses in the New Testament speak of the Triune God. For example, in Ephesians 3:14 through 17 Paul said, “I bow my knees unto the Father... that He would grant you, according to the riches of His glory, to be strengthened with power through His Spirit into the inner man; that Christ may make His home in your hearts through faith.” In these verses we see the Father, the Spirit, and Christ, the Son. Second Corinthians 13:14 also unfolds the Triune God: “The grace of the Lord Jesus Christ, and the love of God, and the fellowship of the Holy Spirit be with you all.” In this verse the three of the Godhead are for His dispensing, for His going out and coming in, that is, for His spreading out and our entering in.
The first mention of man in the whole Bible speaks of him in relation to the Triune God. Genesis 1:26 says, “And God said, Let us make man in our image, after our likeness.” The “us” in this verse refers to the Triune God. Thus, in the verse where man is first mentioned, God is alluded to as being triune. If God were not triune, He would not be able to dispense Himself into us, to work Himself into us, and to mingle Himself with us. But because God is triune, He can enter into human beings. The Father is the source, the Son is the course, and the Spirit is the flow. In this way, the Triune God comes into us.
Three gates on each of the four sides, constituting the number twelve, also imply the mingling of the Triune God with man, God’s creature. The number four signifies the creature (4:6), and the number three, of course, signifies the Triune God. The number twelve does not denote addition but multiplication. Three times four indicates that the Triune God mingles Himself with His creature, man, to produce a composition, a compound.