With the Romans 8:35-39, I believe Paul was encouraging us to take on the same mindset he had about being determined to not allow anything to separate us from the love of Christ. It is clear Paul was not going to allow anything or anyone to separate him from God and named all of those things that could play a factor if we let it. But he was telling us...don't allow it. Don't allow those things to separate you from Christ, He set us free and we do not have to allow these things to separate us...take a look at II Cor 4:8-10, where he also reiterated how hard it was going to get for us as Christians sometimes, but we still are not forsaken by Christ: We are troubled on every side, yet not distressed; we are perplexed, but not in despair; Persecuted, but not forsaken; cast down, but not destroyed; Always bearing about in the body the dying of the Lord Jesus, that the life also of Jesus might be made manifest in our body. For the Heb 6 scriptures...I think you are referring to verses 4-6? First, we know that we can repent and be forgiven of our sins (God's grace is great and he is long suffering), but I believe in this instance Paul is referring to that individual, or former Christian individual, who truly knew Christ, received the Holy Ghost, was living holy, but allowed their flesh to overtake them willfully and continually (which could happen to any Christian if he/she stops doing what it takes to be able to resist the devil). That individual kept tempting Christ, meaning they knew God was loving, had grace and would forgive, so they had the mindset of...well, I'll go a head and sin because I know the Lord will forgive me. That individual made a habit of this and eventually it backfired. Neither let us tempt Christ, as some of them also tempted, and were destroyed of serpents I Cor 10:9. This is why Paul also tells us not to take advantage of God's grace in Romans 6:1-2, there is danger in that: And even as they did not like to retain God in their knowledge, God gave them over to a reprobate mind, to do those things which are not convenient; Rom 1:28, but go on and read all of that through verse 32. Lastly, further in Hebrews, 10:26, Paul warns of that same type of individual from Hebrews 6, who continues to allow sin in their lives: For if we sin wilfully after that we have received the knowledge of the truth, there remaineth no more sacrifice for sins, God knows the heart of each of us, so He is really the only one who can truly judge us properly. You can be a true Christian today, but allow sin to overtake you tomorrow, truly repent and be redeemed...BUT, if you keep doing this on purpose (tempting God), God will judge you when He sees how your heart has turned. This is why Paul tells us to die daily (meaning kill that flesh that wants to sin) on a daily basis. We can't live tomorrow off of that great spiritual day we had today. We have to start all over again each day to live holy one day at a time.