Hebrews 6:4 For it is impossible for those who were once enlightened,(convicted by the Holy Spirt and realized the need for personal salvation) have tasted of the heavenly gift, (The “heavenly gift” being Jesus , “tasted” meaning having received salvation bought and paid for by Christ) and were made partakers of the Holy Ghost, (Having received the Baptism of the Holy Ghost after salvation)
5 And have tasted the good word of God, ( being knowledgeable in the written Word of God) and the powers of the world to come, ( having operated in the gifts if the Spirit)
6 (It is impossible, verse 4) If they shall fall away, to renew them again unto repentance; (loss of salvation) seeing they crucify to themselves the Son of God afresh, and put him to an open shame. (Putting the Son of God to open shame is s grave matter) There are 5 conditions in the above passage. 1 John 5:16 If any man see his brother sin a sin which is not unto death, he shall ask, and he shall give him life for them that sin not unto death. There is a sin unto death: I do not say that he shall pray for it. The question here is this physical death or spiritual death. IMO this is spiritual death because of the wording. The context is a “brother”. I am fully aware that this will be controversial and most likely rejected by those that hold to a strict view of eternal security. Also the doctrines of Baptism of the Holy Spirt and the operation of the gifts of the Spirit are rejected by many. This is not a discussion of those doctrines by a response to the OP with an alternate view.