I think that confusion comes when we fail to separate two different issues. First is salvation which is given as a gift and is God's work alone determined before you are born. Second personal righteousness brings eternal reward and is judged by Him. The irony is that the latter is about walking in the Spirit and yielding to His intent within. So this is not our Work but His through us.
Actually, the confusion came when it was conceived that a person could be made just, and therefore salvageable, without actually
being just as a result. Historically, Christianity had never viewed salvation as a one-time permanent irreversible event, or that one could know with absolute 100% certainty that they were among the number of the saved-and especially if the person was enmeshed in grave sin, producing no good fruit. Passages that speak of salvation to a general audience of followers were never seen as
necessarily applying to all who heard and then claimed them as applying to themselves but were generally viewed as exhortations, encouragements, instructions, warnings, etc, sometimes using hyperbole.
Again, salvation was/is viewed as
union with God, an ongoing relationship, a union which is to begin and blossom here in this life but will only be fully completed and consummated in the next life when we meet Him “face to face”. Meanwhile, “walking in the Spirit and yielding to His intent within” is necessary in order for us to
live according to the bible, and not just for some prizes or rewards in heaven. Jesus will be judging us for how we lived our lives with Matt 25:31-46 forcefully driving home the fact that what we
did in this life will be a major determining factor, along with 2 Tim 4:1, Acts 10;42, and 2 Cor 5:10. Either way, salvation is to be worked out, together with He who works in us (Phil 2:12); our calling and election are to be made sure (2 Pet 1:10).
And, yes, it’s been understood for centuries that this is all grace, that God, Himself, empowers our right actions and the love that motivates them. When He crowns man He’s really only crowning His own work. The question is in whether or not that grace can be
resisted, just as it, just as
He, was initially resisted in Eden. (And, as a sidenote, in His world the dynamics of resistance and struggle can result in overcoming and growth-that’s the world we live in, since Eden, with our choices involved in that struggle, in that process.)
Again, God is
still creating, seeking to produce even greater beings than He began with in Eden and not doing all this so just He can end up stocking heaven with a portion of His creation and stocking hell with the rest. But do we even
want to be and to grow in His likeness and image? We need His grace in order to elicit a “yes”, but yet He does not override our ability to say “no”, by His wise discretion and for His highest purposes for us.
The difference is in whether we as believers can
refuse to yield, can be drawn away from Him and to worldly desires, can turn out to be poor soil in the end, can fail to love as He intends and draws and enables us to. So, rather than putting the cart ahead of the horse we let Him be the final judge.
Having faith is inseparable from producing good fruit, or it’s a dead faith. If we find ourselves producing that fruit we can have a strong assurance that He’s near to us, and that we’ve remained near to Him. If we aren’t doing so, then we’ve strayed regardless of any profession of faith and trust. And we may or may not care enough to repent and return.