Can I open a really deep concern of mine? I've had lots of conversations with friends on this, and with most of them, I have no reason to doubt their salvation. As stated, I just think they're being inconsistent in their theology. But I've had long conversations, as demonstrated in the comments of this posting, that really disturb me. My dear anonymous friend--quite frankly--seemed to be flirting with works salvation. Then I would try to nail down what he actually believed as far as how to be saved, and he'd supposedly affirm salvation by grace thru faith plus nothing. Then we'd go a little bit further, and he'd come right back and say something that sounded all the world like he believed that it's partially his works that'll get him into Heaven! It was rather frustrating at times.
Since I'm being so open here, let me just observe something about our exchange. I've thought thru his arguments and I've come to a sobering conclusion: If someone believes in conditional security, if you'll give them enough time and they're really consistent on this issue, then eventually they'll reveal that they don't really believe in salvation by grace thru faith in Christ alone. How could they not?
Take for example his view of Romans 8:17 versus mine. I look at that verse and--based on the Bible's clear teaching elsewhere that we're saved by grace thru faith in Christ alone--I take it to fall into the very common category of "If you truly belong to Christ, here's how you can tell." But my friend looks at those verses and says "The way to be glorified is by suffering for him." That's works salvation, not what the Bible teaches.
You see, in my view (which I think is the only way to interpret the Bible consistently) the Lord takes the initiative in saving us, then our works are an inevitable response to that. But the way he looks at it, our works cause him to save us.
To all my conditional-security friends, I'd have to ask: "How is he wrong?"
And as a final reminder, if you're interested, I've set up a page that lists my postings on this issue.