The argument for the Immaculate Conception is that Mary had to be pure to be the mother of God and therefore was born without the “stain” of Original Sin. Thomas Aquinas argued that she was born with Original Sin because she said that she acknowledged the need of a Savior Luke 1:46-55, but was later after she accepted the task of bearing Jesus she was cleansed of it. But if either of those positions were true then it would be impossible for Jesus to ever have sinned. But was it? Did Jesus have a conscience?
Original Sin was taught as a “black mark on the soul”, that we were born evil and in need of salvation. Today it is largely taught that we are born good but with the propensity and the ability to commit evil. For me that description seems far more likely. For a sin to be a sin it must be a grave matter done with full knowledge. It is not something which we can do by accident nor by inheritance. The sins of my father were his sins, not mine. The story of Adam & Eve seems to be more focused on the development of a conscience (knowledge of good and evil) therefore what we “inherited” from our first parents was the ability to commit sin rather than the sin itself.
Scripture seems to say that Christ did have the ability to sin. He was tempted in the desert three times. Luke 1:46-55 The temptations were to commit the sins of hedonism (hunger / satisfaction), egoism (spectacular throw / might) and materialism (kingdoms / wealth). But it begs the question of whether or not we can be tempted to do something which we cannot possibly do? I am not tempted to fly to the moon because it is totally impossible for me to do so. I am tempted to rent and R.V. and travel across the country because I can do that. If Jesus did not have the ability to sin then he could not be tempted. If He was tempted then He did have the ability but chose not to sin. Likewise Christ displayed that He had a will of His own which at times differed from the will of God. He asked that His task be taken from Him. But He did the will of God rather than follow His own will.
This is not an argument about whether or not Christ sinned, but whether He had the ability.