I agree that this passage is confusing but yet very clear and understandable.If you want to understand the bible you must first forget everything you ever herd about the passage and let the Holy Spirit teach you. Offten we read a certin passage without study and appliy to it the understanding that another pass on to us without letting the Holy Spirit talk to us. One good example of this is Isa 53:5. If I ask you what that verse is all about 99.9% of you would tell me that it tell us what Jesus did on the cross for us and that by his stripes we here healed from all sickness. You would tell me this because that what all the great pastor preach week after week on tv but you would be wrong. It's important to not assumed what a verse is saying but to study the scriptures (2 Tim 2:15).

Let me start by telling you that God does heal but Isa 53:5 is not a verse to prove it. Jesus clearly told us what he came to do in John 10:10 he was sent from the father to give man life. Adam sin cause death (seperation from God) to enter theis world and death was pass upon all men because we are all decendants of Adam (Rom 5:12-13). God tried to restor life to men through the law but the only thing the law did was make man guilty of there sin (Rom 7:10). So Jesus came to establish a new covenant built on better promises one design to give you life or a restored relationship with God. Isa 53:5 may have been translated as BY HIS STRIPES YOU ARE HEALED but the true meaning is BY HIS STRIPES YOU ARE RESTORED or YOUR RELATIONSHIP WITH GOD WAS RESTORED. The stripes of Jesus gave you life not health.

So if you want to understand what Gen 3:15 is all about first start by forgetting everything you ever hear about it and then let the Holy Spirit talk to you. If you would like my opignon on Gen 3:15 let me know I won't get into it right now because it would take a little while but I would be glad to share it with you.