I would say that unlike the American Legal System, Ignorance is an excuse. However, I am not one hundred percent sure. It can be argued that the New Testament has confliction verses on the issue, but personally I think taken as a whole, the NT does seem to say that ignorance, as opposed to willful ignorance, is an excuse.
In John 9:41 Jesus said to the Pharisees, “If you were blind, you would not have sin. But now that you say, ‘We see,’ your sin remains.” These Pharisees seem to be guilty of willful ignorance. This makes me think of all the Christian clergy, in all denominations, who study the bible and yet teach outrageous things about Christianity.
Then there is also Matthew 18:6 where Jesus said, “If any of you put a stumbling block before one of these little ones who believe in me, it would be better for you if a great millstone were fastened around your neck and you were drowned in the depth of the sea.” This seems to me that Christian teachers are damned even if they are ignorant.
Then there is Hebrews 10:26-27 where the author wrote, “For if we willfully persist in sin after having received the knowledge of the truth, there no longer remains a sacrifice for sins, but a fearful prospect of judgment, and a fury of fire that will consume the adversaries.” To me this means that a Christian who willfully ignores the truth he has received will be damned.
But on the other hand, there are verses that don’t seem to say ignorance is an excuse. For example, there is Matthew 15:14 where Jesus says, “Let them alone; they are blind guides of the blind. And if one blind person guides another, both will fall into a pit.” Here it says the blind/ignorant followers of the blind leaders are also culpable. But maybe, the followers in this verse are willfully blind/ignorant. For example, people who follow the blind preachers of the “Prosperity Gospel” could be in trouble. I mean it’s so obvious that is a false Gospel.
Finally, there is the Parable of the Sheep and Goats found in Matthew 25:31-46. The goats act as if they are innocently ignorant and yet Jesus said, the goats will go away into eternal punishment. The text is not clear about whether or not the goats were willfully ignorant, but that does not rule out Jesus knowing that in their hearts their ignorance was willful.