Mankind had gone astray. Sin and death and he who had the power of death, the devil, had come to power because of the fall into sin, so that our bodies had become slaves of unrighteousness. So something had to happen.

“Who, being in the form of God, did not consider it robbery to be equal with God, but made Himself of no reputation, taking the form of a bondservant, and coming in the likeness of men. And being found in appearance as a man, He humbled Himself and became obedient to the point of death, even the death of the cross.” Phillipians 2:6-8

He came to earth in a human body. His human nature was like ours. Why? Because He actually had to experience what it means to be human in order to condemn the sin which mankind has been bound to. He experienced it and overcame it and in this way overthrew the devil and took his power away.

Yes, as a human being like you and I, Jesus could have given in to the lusts and desires of the flesh and fallen in sin. (Hebrews 4:15) Yet He never gave in to temptation. If this hadn’t been the case, then there would have been absolutely no point to Him being tempted. It was through this overcoming that Satan lost his power.
The devil could not have tempted Jesus to sin (Matthew chapter 4) if he didn’t have a nature to tempt. “For we do not have a High Priest who cannot sympathize with our weaknesses, but was in all points tempted as we are, yet without sin.” Hebrews 4:15 “But each one is tempted when he is drawn away by his own desires and enticed.” James 1:14 We can see by this that temptation is linked to the desires of human nature.
It is not a Biblical phrase. It is the doctrine about Jesus Christ, the Son of God, who came down to earth and put on flesh and blood like us. He was tempted like us, but overcame all sin, by presenting Himself as a sacrifice to God in the power of the eternal Spirit. He was justified in His human spirit, and received up in glory. (Hebrews 4:15; Hebrews 9:14; 1 Timothy 3:16)
When people couldn’t manage to keep the law in the old covenant, they had to offer something in order to be freed from the guilt they had incurred by breaking the law. The offerings for forgiveness had to be repeated because they continually sinned. They could become righteous outwardly, but they could do nothing about inward sins. i.e.“You shall not covet.” Although they were forgiven, their hearts could not be pure.

Jesus came with something completely new. He fulfilled the law both outwardly and inwardly, thus enabling us to do the same. He made it possible for us to get a completely pure heart, by not just being righteous in the outward, but also cleansing the inner thoughts and intents of the heart from such things as envy, hatred, pride, spite, etc. As Christians, we are called not only to receive the forgiveness of sins, but to overcome all sin, to follow Him who committed no sin.

Both Jesus and God testify that He was the Son of God, born of a woman. He was in ALL things made like us (Hebrews 2:17). “And the high priest answered and said to Him, ‘I put you under oath by the living God: Tell us if you are the Christ, the Son of God!’ Jesus said to him, ‘It is as you said.’” Matthew 26:63-64 “And suddenly a voice came from heaven, saying, ‘This is My beloved Son, in whom I am well pleased.” Matthew 3:17
It was the fact that God made the ultimate sacrifice- His only begotten Son – which was so relevant. (John 3:16) No one else could have done it, because the way had not been opened yet. Jesus knew the way before He came to earth as a man, but He had to be made manifest in the flesh in order to show and open up the way for mankind. He did this by living a life of suffering sin in the flesh into death, and overcoming it.

In order to do this for us Jesus let Himself be born into the world as a human being – the Man Jesus Christ. “Therefore, in all things He had to be made like His brethren, that He might be a merciful and faithful High Priest in things pertaining to God, to make propitiation for the sins of the people.” Hebrews 2:17. He is not just an atonement for our sins, and an example we can never follow, but he is our brother and our forerunner.

We are equally equipped to overcome sin as Jesus was. We also have the knowledge of what our task here on earth is – to do God’s will – and we have the Holy Spirit. When Jesus returned to His Father in heaven, He sent the Holy Spirit to help, teach, and give power to those who are tired of their own sin and want to obey God’s laws. We have access to the Father, and we have His Word to guide us as to how our lives should be.