You can ask the question as many times as you want but the answer will still be the same. It is speaking of eternal life because falling away is crucifying Christ again. Christ's death and resurrection were for eternal life, not life here on earth.
Look at verse 8:
"But that which beareth thorns and briers is rejected, and is nigh unto cursing; whose end is to be burned."
It goes a little beyond failing to enter "God's rest", doesn't it? Look at verse 9:
"But, beloved, we are persuaded better things of you, and things that accompany salvation, though we thus speak."
This verse confirms that it is speaking of salvation. It speaks of things that "accompany salvation".
If the answer is the same then you have nothing to offer.
All you are doing is saying to fall away and crucify Christ is speaking of eternal life. Ok. Why? You say because Christ's death and resurrection were for eternal life, not life here. That is a foolish statement. You neglect the walk of sanctification the believer has in this life, which is due to the empowering of the Holy Ghost. See (Rom. 8:13) Such a walk in the Spirit is not possible without Christ's sacrifice. You neglect the maturing aspect of the believer which involves time and experience with God. See (Gal. 3:24-4:6) This is only possible through the sacrifice of Jesus Christ.
No, (Heb. 6:8) does not go beyond entering the Rest of God. Why should it? Just because the term 'fire' is there. Every time you see the word fire does not mean hell or the lake of fire. Every time you see the word baptism doesn't mean water baptism. Paul is turning to an analogy of the earth to describe what he is saying. The earth brings forth both good herbs and thorns and briers. That earth which brings forth good herbs is blessed. That which brings forth thorns and briers is not cursed...it is nigh unto being cursed. As a result the briars and thorns will be burnt off. The briars and thorns are not burned off to destroy the earth.
Therefore the believer who continues on in his walk of salvation will enter the Rest of God here and produce the correct fruit of the Spirit. The believer who stalls due to lack of faith or worldliness will produce thorns and briers and will not enter the Rest of God. God is then busy with them in destroying those thorns and briers which they have produced. They may die in the wilderness, but they are not cursed. They are still God's people.
Concerning (Heb. 6:9), the question never was did it concern salvation. The question was did it concern only the eternal aspect of salvation? Which is what you said it did. Which it does not. Which (6:9) proves. Things that accompany salvation cannot be produced without Christs sacrifice.
So, why does crucifying Christ again mean one loses his eternal life?
Stranger