1) Just because we do not read that he is called Emmanuel within the New testament, this doesn't mean that the people in New testament times did not view him as such.For example. Jesus was worshiped by the Magi.As we know from the scriptures, no one is to be worshiped but God ALONE. Therefore, we can conclude that the wise men believed Jesus to be God in the flesh. If we see sun worshipers worshiping the sun, whether we hear them call it God or not, we know by their actions that this is how they view it. We know by their worship that this is what they call it. In the same way, despite it not being written anywhere in the New testament that he was called Emmanuel, we see that by the wise men worshiping the Christ as God, that they viewed him as Emmanuel. That they called him God with us. For by their actions we can see how they viewed him. By their worship we can see what they called him. They viewed him as God, and he was indeed with them. Emmanuel.


2) When we read the prophecy of Isaiah, nowhere does it say That he would be called God with us ONLY during his (Christ's) time.  So just because the virgin birth came into fulfillment at that specific moment in history doesn't mean that this section of the prophecy is also limited to this exact moment in time as well. The fact of the matter is this: even if Jesus was not called Emmanuel by the people of his time ( which as we saw, is very unlikely) this prophecy still remains in effect to the people of our time and of future generations. The truth is that the majority of Christians within our world today call him Emmanuel and believe him to be God with us, bringing this prophecy into fulfillment.