True however I wouldn't use sin the the flesh as to mean our nature has sin dwelling literally in the flesh but rather the flesh is where sin takes place. It has the propensity to sin.
I use "flesh" as Paul and Peter uses it - our nature. Sin is not in our body. Our body is just a puppet controlled by our nature - our mind and emotions: our spirit and soul. Those have been made immortal. Our body must still die and also be resurrected to be immortal. Romans 8:10.
But we are not in the flesh but in the Spirit, if the Spirit of God indwells us. And if anyone does not have the Spirit of Christ he does not belong to Him. Romans 8:9
When we are born again and Jesus has taken away our sin, He takes it from our nature, the old man. That is why we then partake of the divine
nature of God. Romans 6:6-7; 2 Peter 1:2-4
If God condemned sin in the nature of Jesus Christ, it must of course mean that sin is represented in him. It's the repudiation of the flesh which Christ revealed both in his life and in his death. He crucified the flesh every day in his mind and ultimately he literally crucified the flesh at Calvary.
You seem to believe that Jesus was born with a sin nature, even though He was conceived with the seed of the Father, and that seed remained in Him.
The key is the seed. Why is the seed so important to us? 1 John 3:9.
Whoever has been born of God does not sin, for His seed remains in him; and he cannot sin, because he has been born of God. Jesus never sinned. He was tested in all things, but never sinned. Was it a struggle to not sin as you seem to think? No, and neither is it for the born again. He is our example. He is why it is important for us to be born again to be freed from sin. 1 John 3:5.
Jesus was manifest to TAKE AWAY our sin, and in Him there is no sin. Where did Jesus take away our sin from? Our body? No! Our nature. It is all about our nature. I repeat - 2 Peter 1:2-4.
Grace and peace be multiplied to you in the knowledge of God and of Jesus our Lord, 3 as His divine power has given to us all things that pertain to life and godliness, through the knowledge of Him who called us by glory and virtue, 4 by which have been given to us exceedingly great and precious promises, that through these you may be partakers of the divine nature, having escaped the corruption that is in the world through lust.
Therefore we can conclude that God condemned sin in Christ by putting the source of sin i.e flesh to death by obedience to the Spirit Word.
Sin was not IN Christ. He was sinless. God placed the sin of the world on Him so that when He died, the sin of the world would die also. You somehow believe it was His own sin. That is silly. And Romans 8:1-9 does not teach that. It is OUR sin that Jesus condemned in OUR flesh. That is why we are not in the flesh, but in the Spirit when we have His sinless Spirit inside of us.
Those who have not received God's Spirit and are still struggling with sin, even though they believe everything written about Christ, need to be born again of HIS SPIRIT.
It is all about motive. Those who just see Jesus as a ticket to heaven and just don't want to go to hell are NOT born again. They don't believe IN Jesus, and believe as much as any demon does. But those who love God and want to be scrubbed clean from sin to be like Jesus are the ones whom He fills with His Spirit.