It is for the reason that the flesh of Christ is not of man, but of God. His Word was made flesh.

Isa 7:14 Therefore the Lord himself shall give you a sign; Behold, a virgin shall conceive, and bear a son, and shall call his name Immanuel.

It is the very Word that his flesh is of, not of any man, therefore that flesh is not like our bodies, but it is holy and a perfect propitiation for all men. That body existed not due to man, but the power of the Almighty, his Word. I guess the simple answer to your question brother, before I make myself a fool if I haven't already, is that God cannot lie, that's how. I wouldn't say he was wrapped in sinful flesh though, but sinless flesh, otherwise I don't think he would have been a proper sacrifice for sins. 

I am not your teacher and only wish to share things with you that you may in turn try them by your own knowledge of the Lord. I really don't know any thing. Still learning and growing in the knowledge of our Lord and Savior Jesus Christ. Praying for you and all men that you would also come to the knowledge of the truth and continue to grow in it. I am a sinner, but I have a hope that God through Jesus Christ our Lord will deliver me from my present situation of being a sinner and deliver me from this vile body and I thank him for this promise of eternal life. This is my faith that I share with all my brethren in the Lord who we patiently wait for. Jesus Christ IS come in the flesh.

Rom 8:22-25  For we know that the whole creation groaneth and travaileth in pain together until now. And not only they, but ourselves also, which have the firstfruits of the Spirit, even we ourselves groan within ourselves, waiting for the adoption, to wit, the redemption of our body. For we are saved by hope: but hope that is seen is not hope: for what a man seeth, why doth he yet hope for? But if we hope for that we see not, then do we with patience wait for it.