I'm sorry, I don't follow that sentence because it is stated without explanation.
But of course I can demonstrate it Biblically, and not just with the Scriptural text of 2 Maccabees which for some reason you apparently dismiss de facto. But the concept of Purgation for example:
Heb. 12:7-10 Endure hardship as discipline; God is treating you as his children. For what children are not disciplined by their father? 8 If you are not disciplinedand everyone undergoes disciplinethen you are not legitimate, not true sons and daughters at all. 9 Moreover, we have all had human fathers who disciplined us and we respected them for it. How much more should we submit to the Father of spirits and live! 10 They disciplined us for a little while as they thought best; but God disciplines us for our good, in order that we may share in his holiness.
Now if what Christ did was "for all" in the sense that you mean it, then why would God need to chastise people who are
already His children because they
aren't at the degree of holiness they should be? Doesn't God know He doesn't need to make any of those who are already His children any holier? Why is He punishing them? Doesn't God know Jesus paid all debt?
Of course, this text shows that even those who are already God's children need to be made holier. This is called sanctification. And that's echoed in the last sentence of the Catechism paragraph I just cited you. The concept of an instantaneous perfection is fictitious, as we see in Scripture, and simply in watching good fellow Christians who still stumble and sin now and then. That is not a quality compatible with the perfection of heaven in which no such blemish can enter (Rev. 21:27).
As I said already (which went unaddressed), the Bible speaks of the need for sanctification quite a bit, even after initial justification. That of course takes nothing away from Christ's sacrifice
but is an extension of its effects. For by no other power can sanctification occur either.
Another way to look at it is to ask yourself: Do I still sin occasionally? The answer is yes. Then ask, is that quality compatible with heaven? The answer is no. So somewhere between earth and heaven, there will be a transformation.