According to Christian theology the sacrifice of Christ is necessary for us to be saved. This appears to imply that no human can live sin free. This suggests to me that humans are sinful by nature. Is it correct to say that this nature comes from God?
The power to choose comes from God, and with it the power to do evil. There is no possible way for us to have free will without the ability to abuse it. And the abuse of free will leads to evil in the world. C.S. Lewis explains it this way:
"We can, perhaps, conceive of a world in which God corrected the results of this abuse of free will by His creatures at every moment: so that a wooden beam became soft as grass when it was used as a weapon, and the air refused to obey me if I attempted to set up in it the sound waves that carry lies or insults. But such a world would be one in which wrong actions were impossible, and in which, therefore, freedom of the will would be void; nay if the principle were carried out to its logical conclusion, evil thoughts would be impossible, for the cerebral matter which we use in thinking would refuse its task when we attempted to frame them."
However, free will is not absolute because we inherit the sinfulness, or brokenness, of our ancestors. Their propensities to addiction become ours, and we take on their personality flaws. I was just reading that there is a new field called "epigenetics," where scientists are finding that choices we make affect the expression of our DNA even for the next generation. So there is actually a connection between choice and DNA. As the narrator of the novel Gilead says, we "live in the ruins of other generations." None of us have within us the potential to reach our full humanity.
But God planned from the very beginning that he would take upon himself the consequences of free will by giving full reign to evil during his passion. The penalty for every sin that was ever committed or will ever be committed was paid in full by him. He did for us what we could not do for ourselves, and "rendered powerless him who had the power of death, that is, the devil" (Hebrews 2:14).
He also broke the domino effect of generational sin by becoming the first perfect human. Not only was he fully God, but he represented humanity at its highest and best. And by his blood we were redeemed from the "futile way of life" handed down by our ancestors (1 Peter 1:18), to receive his Holy Spirit and become like him--the "firstborn of many brethren" (Romans 8:29).
But in order to receive his Holy Spirit, we have to surrender the will that is set against him. "Behold, I stand at the door and knock; if anyone hears My voice and opens the door, I will come in to him and will dine with him, and he with Me" (Revelation 3:20). And the more we yield to his Spirit, the more our will conforms to his. He will give us his shalom--or harmony with him, ourselves, and other people, and he makes us fully human and fully free.