What's Wrong With Jim Martin's Misunderstanding Of Un/marked Theme?

(1) Applying Martin's model yields:

Blessed	are	those who hunger and thirst for righteousness
Theme: marked	Rheme	Theme: unmarked

That is, the clause as message is deemed to have two 'points of departure', one at the beginning and one at the end, both providing the context for the body of the message, which is simply 'are'.

Cf Halliday's version of Halliday's theory:

Blessed	are	those who hunger and thirst for righteousness
Theme: marked	Rheme
Attribute	Process: relational	Carrier
Complement	Finite	Subject
Residue	Mood

(2) Applying Martin's model yields:

Sad	therefore	in his view	is	how to describe it
Theme: marked	Rh-	Theme: marked	-eme	Theme: unmarked

That is, the clause as message is deemed to have three 'points of departure', one at the beginning, one in the middle and one at the end, each providing the context for the body of the message, which is the discontinuous Rheme 'therefore…is'.

Cf Halliday's version of Halliday's theory:

Sad	therefore	in his view	is	how to describe it
Theme: marked	Rheme
Attribute		Angle	Process: relational	Carrier
Complement	conjunctive Adjunct	circumstantial Adjunct	Finite	Subject
Residue			Mood

For the paradigmatic opposition of unmarked and marked Theme, see here.