Peter did say we can backslide to a seared conscience and forget that we have been purged in Christ.....sin is sin......a white lie is as much of a sin as murder......
For the record....Only God can judge for sure.....regardless....this whole Bruce to Caitlyn deal makes me want to spew........!
I believe there are some failings worse than others. What you say about "a white lie is as much of a sin as murder..." is true in that a small lie and murder are both transgressions, but that is where their comparisons end. I believe there are mortal sins and venial sins much like what 1 John 5:17 speaks of. If there were no distinctions why would Paul in Romans 11:22 warn the Romans of being cut off? Even losing one's salvation in Corinthians 9:27?
I believe there are some sins particularly abominable to God and will go further in saying that cross dressing is one of them. This is not biblically provable, it's more like something observable by human nature. Humans are made in the image of God and I believe humans have an inherent understanding of SOME Godly things, however obscured. I personally believe this kind of sin is mortal in nature and that Jenner's salvation is in jeopardy. I also believe what Jenner is "hearing" about himself is a lie. A lie perpetrated in order to repulse God and ensure another lost soul. There are simply larger motives at work here than a guy in a dress.