The angels are 'sons of God', Adam and his children are 'sons' of God, even Lucifer himself is considered a 'son' of God. This is why there is the distinction between the sons of God and the sons of the Devil. Of course Christ is the 'son' of God as He was born through the same family line as King David, who was born directly from Adam.
You are correct, He was simply that 'Word', but it was that same 'Word' that spoke everything into being. Many people may have a hard time grasping the 'meat' of what you are getting across. There are many 'new' Christians that will barely grasp the 'milk' of the message much less understand what the Logos really represents.
The distinction about the 'son' of God is that it is His spirit manifest into the physical. When Adam was 'formed' (not created like those found in Gen 1:26) he was given the 'breath of life' or spirit of God in his nostrils. In the Ferrar Fenton translation Adam was called a 'Representative' of God, thus having this spirit, there was now a direct image of God on earth.
Through Satan in Eden, Eve was beguiled, wholly seduced, and she bare Cain as a result. The descendancy of Cain is represented as the 'children of the devil' or 'OF that wicked one'. Recall John 8:44 for example, Jesus is speaking to a literal descendant of Satan, not just someone who is spiritually corrupt. If they are 'of' that wicked one, then they to are wicked and cannot be brought to light.
As Adam was born of God, and through him Christ came, and God is 'The Father', then all who are of the Adamic creation, are 'of' God, and considered His children.