In addition, I have two other questions. The first is whether or not what Paul said is general. Is it absolutely impossible for former Christians to become Christians again?
Second, is Paul saying that it's impossible for former Christians to become Christians again because that would require Christ to be sacrificed again for these people? He said that those who apostatize crucify Christ again, and obviously, that can't be done.
THERE IS ONLY ONE SIN that cannot be forgive, the blasphemy against the Spirit of God. As before stated a full study article on that subject is on my website.
When I take the above into consideration, I have to end up saying this is a GENERAL statement. Like the one in Luke where it is said, ALL the world came to be taxed - and that is most certainly a "general" statement, we know the people in China, Brazil, Japan, etc never came to be taxed in the Holy Land.
I cannot see that God would close the door of salvation to someone who must repent of leaving the faith of God, then later seeing their mistake, and repenting.
Maybe in Paul's time some had left the faith, and Paul knew not one who came back to God and Christianity.....hence a general statement by Paul but he could not qualify it because he never knew anyone leaving true Christianity, and then later repenting of that error, sin, and again back in the faith and grace of God.
I think Paul is saying the words about crucifying Christ again, as a warning to Christians, that once partaking of the things of heaven, you let them slip away, it is hard, maybe very hard, to find space to repent again.
Once more maybe Paul had never encountered a person leaving true Christianity, and later repenting of so doing, and coming back to the true Christian faith.
It is just not possible from the character of God, to NOT forgive such a person. As Jesus said there is only one sin that cannot be forgiven in this life and in that to come.....the blasphemy against the Holy Spirit.
So Paul is giving a "general" statement, that must have exceptions, but he himself may not have seen the exception.
And Paul was with this section and in Hebrews 10, getting the point across that it is a mighty serious decision, to leaving true Christianity, when you had experienced all the heavenly gifts Paul mentions.