1) They were once partakers/participant of the Holy Ghost.
2) They were once enlightened.
3) They did taste of the heavenly gift/Salvation.
4) They did taste of the good Word of God.
5) They experienced the works of power by the Holy Spirit.
6) They saw of a coming age.
7) They fell away/apostatize aka committed Blaspheme againist the Holy Spirit!
8) It is impossible for them to renew a change of their heart/repentance.
9) Because they crucify to themselves the Son of God afresh, and put him to an open shame.
Hebrews 6
4. For it is impossible for those who were once enlightened, and have tasted of the heavenly gift, and were made partakers of the Holy Ghost,
5. And have tasted the good word of God, and the powers of the world to come,
6. If they shall fall away, to renew them again unto repentance; seeing they crucify to themselves the Son of God afresh, and put him to an open shame.
I have a question, I am sorry if it was already answered. Do you believe that if you are saved at one point, then fall out of grace, that you cannot be saved again?