“Behold, a virgin shall be with child, and shall bring forth a son, and they shall call his name Emmanuel, which being interpreted is, God with us.”
As noted above, Jesus is God by nature, and when He was here physically 2,000 years ago, or when His Spirit lives in our hearts, God is truly with us. Not only is the Son of God with us when He is in our hearts, but His Father is also with us in Christ, for “God was in Christ, reconciling the world unto himself” (2 Corinthians 5:19). If we have the Son of God in our hearts we cannot help but have “God with us.” Jesus said, “If a man love me, he will keep my words: and my Father will love him, and we will come unto him, and make our abode with him” (John 14:23). Jesus is the only way to have God with us. Whether the word “God” in Matthew 1:23 refers to the Father or His Son is immaterial. It could refer to either of them without the slightest hint that God is a trinity.