I am not sure where this will go, but I am going to address some of CovertOps points (and maybe others) by writing up an outline of the Combat chapter starting with page 269, Attacks and Defenses. Where I think it is relevant, I'll add parenthetical remarks.
Attack and Defenses (Including Making an Attack (Shaded Box))
...Attack Type
......Melee Attack
......Ranged Attack
......Close Attack
......Area Attack
......Areas of Effect
...Choosing Targets
......Range
......Seeing and Targeting
...Attack Roll
...Defenses
...Attack Results (includes shaded box defining Critical Hits)
......Damage
......Resistance and Vulnerability
......Conditions
......Insubstantial
......Ongoing Damage
......Critical Hits (explains Critical Hits in more detail that the basic definition from page 276)
......Forced Movement
...Durations
...Saving Throws
Attack Modifier (and then it goes on from there, but with nothing else relevant to Critical Hits)
Since it is relevant, a couple of quotes (copy and paste from the Rules Compendium where I could):
(page 269)
Making an Attack
All attacks follow the same basic procedure:
1. Choose that attack type...
2. Choose targets...
3. Make an attack roll
4. Compare your attack roll to the target' s defense to determine whether you hit or miss.
(page 276, Attack Results)
Hit
If the attack roll is higher than or equal to the defense score, the attack hits and deals damage, has a special effect, or both.
Automatic Hit: If you roll a natural 20 (the die shows a 20), your attack automatically hits.
Critical Hit: If you roll a natural 20 (the die shows a 20), your attack might be a critical hit. A critical hit deals maximum damage, and some powers and magic items have an extra effect on a critical hit.
(page 278, Critical Hit)
Natural 20: If you roll a 20 on the die when making an attack roll, you score a critical hit if your total attack roll is high enough to hit your target’s defense. If your attack roll is too low to score a critical hit, you still hit automatically.
Precision: Some class features and powers allow you to score a critical hit when you roll numbers other than 20 (only a natural 20 is an automatic hit).
Maximum Damage: Rather than roll damage, determine the maximum damage you can roll with your attack. This is your critical damage. (Attacks that don’t deal damage still don’t deal damage on a critical hit.)
Extra Damage: Magic weapons and implements, as well as high crit weapons, can increase the damage you deal when you score a critical hit. If this extra damage is a die roll, it’s not automatically maximum damage; you add the result of the roll.
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Interesting.
1. The general rule requires checking the results for a hit or miss.
2. The Attack Results rules on Hit (a higher level rule that Critical Hit) defines the first case where you might get a critical hit (a natural 20) and sates that a critical hit deals maximum damage (plus whatever items and powers might give you)
3. The Critical Hit rules again state the natural 20 case, and then introduce the concept (Precision) that other numbers might
allow you to score a critical hit if a feature or power so stated. Precision, as a modification to the natural 20 rule fro Critical Hit, also reminds us that in this context, only a natural 20 is an automatic hit (so we don't think a 19 will hit if it does not score a critical hit).
It's worth noting that Critical Hit is in the "Hit" section under Attack Results in the intial defintion on page 276 and under "Attack Results" in the further explanation on page 278, as I think I once saw it stated, under "damage."
ALL of that material is around when one MIGHT score a critical hit and how to know if the possibility turns into an actuality.
Along comes Holy Ardor, throwing a HIUGE curve ball:
Whenever you make two attack rolls because of your oath of enmity, you score a critical hit if both dice have the same roll, except if both rolls are 1.
There is no wiggle room in the language. It defines an entirely new case where you score a critical hit. This is a very gigantic departure form the previous rule, but the language is clear - under these circumstances, you score a critical hit.
Now we know from page 276 that a (successful) critical hit requires you to apply critical damage, and also that it is a type of hit.
This is the simplest and most consistent way to read this.
Holy Ardor simply creates a new exception to the rules - a new situation where you score a critical hit.
It's not the only way to read it, of course.
After reading all the argument, my opinion (FWIW) is:
1.
The most straightforward way to read this is that Holy Ardor creates a new exception where OoE doubles = score a critical hit so long if they are not double ones. Once you "score a critical hit" you apply critical damage and any possible effects from hitting, as normal for scoring a crtical hit.
2. While I think it ignores the context of Precision, it is not completely unreasonable to view Precision as overriding Holy Ardor such that you don't get what amounts to an automatic hit from doubles. This is a possible reading of the Precision "rule" due to the imprecise nature with which that rule was written.

This is the
only way to override the clear "score a critical hit" language in Holy Ardor.
3. I think it is completely unreasonable and defies common sense (and the rules) to think it is possible to "score a critical hit" and yet still miss. This also potentially generates some very weird results.