John Darby I found to be helpful.
In the infancy spoken of in verses 1, 2, the obscurity of the revelations of the Messiah, announced at most by promises and prophecies, left worshipers under the yoke of ceremonies and figures, although in possession of some fundamental truths. His exaltation made way for the power of the Holy Ghost here below: and on this the responsibility of souls which had tasted it depended.Now doesn't that make it all make more sense?
The doctrine of the Person and the glory of Jesus forms the subject of revelation in the epistle, and was the means of deliverance for the Jews from the whole system which had been such a heavy burden on their hearts; it should prevent their forsaking the state described in verses 4 and 5, in order to return into the weakness and (Christ having come) the carnal state of verse 1 and 2.
The epistle then does not desire to establish again the true but elementary doctrines which belonged to the times when Christ was not manifested, but to go forward to the full revelation of His glory and position according to the counsels of God revealed in the word.
The Holy Ghost would not go back again to these former things, because new things had been brought in in connection with the heavenly glory of the Messiah, namely, Christianity characterised by the power of the Holy Ghost.
But if any one who had been brought under that power, who had known it, should afterwards abandon it, he could not be renewed again to repentance. The former things of Judaism must be, and were, left behind by that into which he had entered. Christians could not deal with souls by them; and, as for the new things, he had given them up. All God's means had been employed for him and had produced nothing.
The author of Hebrews is writing to Jewish folk. He's telling them that under Judaism they didn't have it all. They were only given milk. Now that Christ has come, they can have more of God. They aren't stuck to ceremonies and sacrifices. And once you've experienced that "moreness" then if you repudiate it....you can't have it back it again.
Oh and it was Matthew Henry who helped me gain some understanding to that falling away talked about in this passage.
The apostle is not speaking of the falling away of mere professors, never convinced or influenced by the gospel. Such have nothing to fall away from, but an empty name, or hypocritical profession. Neither is he speaking of partial declinings or backslidings. Nor are such sins meant, as Christians fall into through the strength of temptations, or the power of some worldly or fleshly lust. But the falling away here mentioned, is an open and avowed renouncing of Christ, from enmity of heart against him, his cause, and people, by men approving in their minds the deeds of his murderers, and all this after they have received the knowledge of the truth, and tasted some of its comforts. Of these it is said, that it is impossible to renew them again unto repentance. Not because the blood of Christ is not sufficient to obtain pardon for this sin; but this sin, in its very nature, is opposite to repentance and every thing that leads to it.Makes more sense to me anyways. :)
I am glad that God gave us men that would intently study God's word so that they can help others of us understand it better too. :)