Why Islam is truth not Christianity

As my opponent has not supplied a rebuttal, I will move on to another point which he brought up in a previous post - the doctrine of salvation. It says in the Quran 53:38 "Whoever goes aright, for his own soul he goes aright; and whoever goes astray, to his own detriment he goes astray. And no bearer of a burden bears another's burden..." Also, in Quran 6:165 "...no soul earns (evil) but against itself. Nor does a bearer of a burden bear the burden of another." This is very similar to the Christian verse "The fathers shall not be put to death for the children, neither shall the children be put to death for the fathers: every man shall be put to death for his own sin." from Deuteronomy 24:16 It is held as truth by both religions that a man or woman who sins is punished for their sins, but not for those actions which are the result of another. The exact interpretation of this - such as the extent to which culture and upbringing excuse an individual's actions - is a topic for another time. For now I shall take these verses at face value; if I do something of my own free will I hold the consequence for it, and I cannot make another take that consequence instead of me. At this point we now hit the juncture between Islam and Christianity. Though both believe that each individual is responsible for their sins, they differ in how that individual can atone for their mistakes. In Islam the responsibility rests solely upon the person, and the end result is that all good deeds are weighed against all bad deeds. Should there be more good than bad, then the person was good. Islam also believes that it is possible for a human to live a sinless life - through discipline, good parents, dedication to scripture, and a righteous environment (a religious government). Whether an individual enters heaven is a direct result of their own actions. Christianity instead believes that man is innately sinful. There is nothing a man can do to become perfect, and at the end of the day he is completely dependent upon the mercy of God for salvation and admittance into heaven. Some say that one must "accept Christ into their heart," which is a poetic nicety. Christ says that, "[he is] the way, and the truth, and the life; no one comes to the Father but through [him]." (John 14:6) To reconcile these two beliefs on salvation and entering heaven, I will pose a philosophical question: If God could have designed man perfectly, and instead chose to design man with the ability to sin, then whose fault is it that man sins? In the Garden of Eden, it was Adam and Eve who ate the fruit - but who planted the tree in the garden so that they could get to it? Who let them eat it? This is a question that can be extremely dangerous in a theological sense, so I will tread with care along what is relevant to this debate. Logically, I choose to kill and therefore I am at fault, but God gave be the ability to choose, therefore He is at fault for my having a choice to begin with. Additionally, God could at any point intervene in any action to prevent a sin from occurring. As I am deciding to sin, God could manifest an angel to say, "Woah, hold on now. I'm an angel, and God disproves." And yet he doesn't. But the crucifixion addresses this: God died on the cross for our sins; He admitted that all pain and suffering results from His design, that all sin ultimately rests with Him, and took ownership of it. A Christian who fails to live perfectly knows that God will have mercy because God understands, more than we possibly can, that perfection is an impossibility. Compare this to Islam, which states that Jesus never died and that all men must make their own way into heaven. In Islam, God purposefully designed mankind that we should struggle to be good so that we might not make it into heaven. Would God give gills to a fish, and make vast oceans and lakes, and then place the fish in a desert so that it struggles and dies? Would God make heaven, and demand perfection as the entry fee, and then make humans incapable of perfection? A child will not be put to death for the sins of the father, and no man shall bear the burden for the actions of another man, but all mankind will bear the burden of their sins which are only possible because of the actions of their Creator. And that creator has taken no ownership of this conundrum. Would God look at a soul and say, "I gave you free will, and you used it to steal because I also gave you hunger and desperation. This makes it your fault." If God is a good, and if He is just, and if He made man, and if man is evil, then the sacrifice of a divine Jesus, and salvation through mercy, is a necessity.