Hebrews 6:6 [6]if they fall away, to renew them again…

Hebrews 6:6
[6]if they fall away, to renew them again to repentance, since they crucify again for themselves the Son of God, and put Him to an open shame.

How can some teach that this is reffering to a believer of Jesus who falls away from faith in Christ?
That belief is really contrary to this…
I John 1:9
[9]If we confess our sins, He is faithful and just to forgive us our sins and to cleanse us from all unrighteousness.

So which is it? 1 John 1:9 or what some believe about Hebrews 6:6?
1 John 1:9 is clear that God forgives anyone who confesses, yet according to Hebrews..
Hebrews 6:4
[4]For it is impossible for those who were once enlightened, and have tasted the heavenly gift, and have become partakers of the Holy Spirit,

Does “impossible” mean impossible?
Does “faithful and just” mean faithful and just?

If you read everything leading up to Hebrews 6 it is obvious that the writer is not reffering those who have “obeyed” and “believed” the gospel.

Lets look at another passage that some find difficult.

Hebrews 10:26-27
[26]For if we sin willfully after we have received the knowledge of the truth, there no longer remains a sacrifice for sins,
[27]but a certain fearful expectation of judgment, and fiery indignation which will devour the adversaries.

The writer mentions “a sacrifice for sins” for a good reason, the Jews offered animal sacrifices all the time as sin offerings.
This is reffering to the same group of people who reject the gospel, even after having heard it.
That is the “willful sin” mentioned here, the rejection of Jesus…
Hebrews 10:28-29
[28]Anyone who has rejected Moses’ law dies without mercy on the testimony of two or three witnesses.
[29]Of how much worse punishment, do you suppose, will he be thought worthy who has trampled the Son of God underfoot, counted the blood of the covenant by which he was sanctified a common thing, and insulted the Spirit of grace?

Nothing suggests that “trampling the Son of God undefoot” and “insulting the Spirit of grace” is accepting the offering of Christ.
The blood “sanctifies” everyone, but that does not mean that all will recieve it for attonement, we can be saved, but not all will be saved.
It is only “whosoever” “believes” according to John 3:16.