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.
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Why then do they not call him Emmanuel instead of Jesus Christ? Because the text says not “you shall call” but “his name shall be called.” This means that the multitude and the outcome of the events themselves will cause him to be called Emmanuel. For here he puts the event as a name. This is customary in Scripture, to substitute names for the actual events. Therefore to say “they shall call him ‘Emmanuel’ ” means nothing else than that they shall see God among us. Admittedly God has always been among us, but never before so openly. The Gospel of Matthew, Homily