you said (quoted) "Those who claim that it was not possible for Christ to sin, cannot believe that He really took upon Himself human nature"

The warfare against self is the greatest battle that was ever fought. The yielding of self, surrendering all to the will of God, requires a struggle; but the soul must submit to God before it can be renewed in holiness. {SC 43.3}

The warfare against self is the greatest battle that was ever fought. The yielding of self, surrendering all to the will of God and being clothed with humility, possessing that love that is pure, peaceable, and easy to be entreated, full of gentleness and good fruits, is not an easy attainment. And yet it is his privilege and his duty to be a perfect overcomer here. The soul must submit to God before it can be renewed in knowledge and true holiness. {3T 106.2}

The Christian life is a battle and a march. But the victory to be gained is not won by human power. The field of conflict is the domain of the heart. The battle which we have to fight--the greatest battle that was ever fought by man--is the surrender of self to the will of God, the yielding of the heart to the sovereignty of love. The old nature, born of blood and of the will of the flesh, cannot inherit the kingdom of God. The hereditary tendencies, the former habits, must be given up. {MB 141.2}

He who determines to enter the spiritual kingdom will find that all the powers and passions of an unregenerate nature, backed by the forces of the kingdom of darkness, are arrayed against him. Selfishness and pride will make a stand against anything that would show them to be sinful. We cannot, of ourselves, conquer the evil desires and habits that strive for the mastery. We cannot overcome the mighty foe who holds us in his thrall. God alone can give us the victory. He desires us to have the mastery over ourselves, our own will and ways. But He cannot work in us without our consent and co-operation. The divine Spirit works through the faculties and powers given to man. Our energies are required to co-operate with God. {MB 141.3}

Jesus Himself, while He dwelt among men, was often in prayer. Our Saviour identified Himself with our needs and weakness, in that He became a suppliant, a petitioner, seeking from His Father fresh supplies of strength, that He might come forth braced for duty and trial. He is our example in all things. He is a brother in our infirmities, "in all points tempted like as we are;" but as the sinless one His nature recoiled from evil; He endured struggles and torture of soul in a world of sin. His humanity made prayer a necessity and a privilege. He found comfort and joy in communion with His Father. And if the Saviour of men, the Son of God, felt the need of prayer, how much more should feeble, sinful mortals feel the necessity of fervent, constant prayer. {SC 93.4}

As one of us He was to give an example of obedience. For this He took upon Himself our nature, and passed through our experiences. "In all things it behooved Him to be made like unto His brethren." Hebrews 2:17. If we had to bear anything which Jesus did not endure, then upon this point Satan would represent the power of God as insufficient for us. Therefore Jesus was "in all points tempted like as we are." Hebrews 4:15. He endured every trial to which we are subject. And He exercised in His own behalf no power that is not freely offered to us. As man, He met temptation, and overcame in the strength given Him from God. He says, "I delight to do Thy will, O My God: yea, Thy law is within My heart." Psalm 40:8. As He went about doing good, and healing all who were afflicted by Satan, He made plain to men the character of God's law and the nature of His service. His life testifies that it is possible for us also to obey the law of God. {DA 24.2}

Bear in mind that Christ's overcoming and obedience is that of a true human being. In our conclusions, we make many mistakes because of our erroneous views of the human nature of our Lord. When we give to His human nature a power that it is not possible for man to have in his conflicts with Satan, we destroy the completeness of His humanity. His imputed grace and power He gives to all who receive Him by faith. The obedience of Christ to His Father was the same obedience that is required of man. {3SM 139.4}

Man cannot overcome Satan's temptations without divine power to combine with His instrumentality. So with Jesus Christ, He could lay hold of divine power. He came not to our world to give the obedience of a lesser God to a greater, but as a man to obey God's Holy Law, and in this way He is our example. {3SM 140.1}

RH.1875-04-01
It was a difficult task for the Prince of Life to carry out the plan which he had undertaken for the salvation of man, in clothing his divinity with humanity. He had received honor in the heavenly courts, and was familiar with absolute power. It was as difficult for him to keep the level of humanity as it is for men to rise above the low level of their depraved natures, and be partakers of the divine nature.

Christ was put to the closest test, requiring the strength of all his faculties to resist the inclination when in danger, to use his power to deliver himself from peril, and triumph over the power of the prince of darkness. Satan showed his knowledge of the weak points of the human heart, and put forth his utmost power to take advantage of the weakness of the humanity which Christ had assumed in order to overcome his temptations on man's account.