πας + substantival participle, which is the substantive?

Greek Koine and Biblical and Medieval Greek
1

A passage containing the construction in question is 1 John 5:1–πᾶς ὁ πιστεύων ὅτι Ἰησοῦς ἐστιν ὁ Χριστὸς…

What is the subject of the above clause? Is it πᾶς, with ὁ πιστεύων acting as a modifying adjective? Or is the subject ὁ πιστεύων, with πᾶς acting as a modifying adjective? Or is the whole phrase to be considered the subject?

I know that πᾶς can act as a pronominal adjective, and hence as a substantive. I have also considered the different positions adjectives can take in relation to nouns (1st, 2nd, 3rd attributive), but that hasn’t helped me arrive at a conclusion.

Thanks for the help.

2

Technically speaking the article with πίστευων makes that the subject, but πᾶς ὁ πιστεύων is a single conglomerate expression. Here the entire phrase πᾶς ὁ πιστεύων ὅτι Ἰησοῦς ἐστιν ὁ Χριστὸς constitutes the subject of the sentence.