You make too many assumptions.
If we had Merciful Wrath glyph
If we had Divine Purpose proc more often.
I only used "if" one time (in my post before yours, and not in that context your're trying to tell me .

If you specc into Divine Purpose, your substainded damage will increase. But it's random.
Here it is - and that's just a fact, since most people use Holy Avenger and sometimes Sanctified Wrath.

If we had Merciful Wrath glyph
I said i would help us - combined with Divine Purpose - to have a better substainded damage.

If we had Divine Purpose proc more often.
And here i talked about what Divine Purpose pro and con.