If i understand what you believe it is this (please correct me if I'm wrong)... a certain sin or sins can't keep you from salvation, but rather if you make a conscious choice to live a lifestyle of sin even after knowing the truth of Christ then you will lose your salvation.

In Heb 10:26 when it says "For if we sin willfully after we have received the knowledge of the truth..."
I would argue that receiving the knowledge of the truth is not the same as being saved. Many have heard the truth and have rejected it, like those in the passage. I understand that he was writing to a church of believer's, but it is possible and I'd even say likely that some of the people in the church hadn't received Christ as their Lord and Savior yet and the passage is warning them that just knowing the truth isn't enough. Please understand that I'm not stating these things as facts, I'm just trying to come to a better understanding of my position in Christ. If you think something I've said is totally out of line please let me know with the love of christ :)

Here are some verses i have found on the assurance of salvation (because ultimately what I think doesn't matter, but what God has to say does.)

Romans 8:38-39: "For I am convinced that neither death nor life, neither angels nor demons, neither the present nor the future, nor any powers, 39neither height nor depth, nor anything else in all creation, will be able to separate us from the love of God that is in Christ Jesus our Lord."

If nothing can separate us from the love of Christ doesn't that include ourselves?

1 John 5:13: I write these things to you who believe in the name of the Son of God so that you may know that you have eternal life.

John is using the word "have" in the present tense, meaning the moment we die to sin and are born in Christ eternal life has begun. If we receive eternal life the moment we are saved how long does that last? Eternal life is eternal, if its possible to lose eternal life then its possible to have ETERNAL life for only a period of time. (which the very name implies is impossible)

Thank you so much for your comments, I've really enjoyed taking a deeper look into this topic. Please continue to post any thoughts or concerns you have. Great Job with the website Michael, I think it's great that you take the time to do this.