Ans. He was true man, because man had offended, and justice required that man should suffer and make satisfaction, and so it is written (1 Cor 15:21). 'For since by man came death, by man came also the resurrection of the dead.' And again, 'All we like sheep have gone astray;—and the Lord hath laid on him the iniquity of us all.' And in 1 Peter 2:24 where that 53rd of Isaiah is mentioned, he saith, 'Who his own self bare our sins in his own body on the tree, that we, being dead to sins, should live unto righteousness; by whose stripes ye were healed.' And again, God did prepare this body, the human nature of Christ, that it should be a sacrifice for sins, 'wherefore—he saith, Sacrifice and offering [that is, such as were offered by the law of Moses] thou wouldest not, but a body hast thou prepared me' (Heb 10:5). In the body which God had prepared for him, which he took of the virgin (Gal 4:4) in this he did bear all the sins of all his elect (1 Peter 2:24).
And he must needs be true God, because, it was an infinite God that was transgressed against, and justice required an infinite satisfaction, and therefore he must be infinite that must give this satisfaction, or else justice could not be satisfied, and so it was written, where the apostle is telling the pastors of the church of Ephesus, by what they were redeemed, he tells them, that God did purchase them 'with his own blood' (Acts 20:28). See 1 John 3:16 where he saith, 'Hereby perceive we the love of God, because he laid down his life for us.' Not in his divine, but in his human nature; for as I said before, God's Christ was of both natures (Rom 9:5; 1 John 5:20; John 1:1-14). True God, and true man, and the divine nature did enable him to undergo in his human nature, all that sin, curse, and wrath that was laid upon him for us; and to overcome, and obtain eternal redemption for us (Heb 9:24).
Quest. How did this Christ bring in redemption for man?
Ans. (1.) Why first, man broke the law of God; but this man did fulfil it again, and became the end of it 'for righteousness to every one that believeth' (Rom 10:4).
(2.) Man was foiled and overcome by the devil; but this Man Christ did overcome him again, and that for us (Luke 4; Heb 2:14,15).
(3.) Man did lose the glory of God, but this Man hath obtained it again.
(4.) Man by sin lost eternal salvation; but this Man by his own blood hath obtained it again for him (Heb 9:12).
(5.) Man by sin brought death into the world (Rom 5:12). But Jesus Christ, that Man, hath destroyed it again (Heb 2:14 compared with Hosea 13:14) and brought in life and immortality (2 Tim 1:10; Rom 5:15).
Quest. But how are we justified by this man's obedience?
Ans. All our iniquities were laid upon him (Isa 53:6,8,11,12). And his righteousness is bestowed on us, if we believe, as it is written, 'Even the righteousness of God which is by faith of Jesus Christ unto all and upon all them that believe' (Rom 3:22). And this is it which Paul so much sought after, when he saith, 'Yea doubtless, and I count all things but loss,—and do count them but dung, that I may win Christ, and be found in him, not having mine own righteousness, which is of the law, but that which is through the faith of Christ, the righteousness which is of God by faith' (Phil 3:8,9).