Divine law is either ius divinum positivum or ius divinum naturale, depending on whether it is revealed or known by reason itself based on the nature of things.
I mean *which* divine law? What is needed is, say for example, against the 1st or 2nd or ? commandment, or reference the pertinent divine revelation from Scripture, this is what is necessary. To say anything is against Divine Law necessarily must at least be able to reference the specific Divine Law itself.
Quote from: Leo XIII, Satis cognitum
it is absurd to imagine that he who is outside can command in the Church.
Calling the proposition absurd, Leo XIII implies that it is known by reason itself that he who isn't even a member, cannot be head; hence this is ius divinum naturale.
The problem is the pope, albeit arguably, is not outside.
Quote from: Pius XII, Mystici corporis
For not every offense, although it may be a grave evil, is such as by its very own nature to sever a man from the Body of the Church, as does schism or heresy or apostasy.
Pius XII says that schism, heresy, and apostasy are offenses which by their very own nature sever a man from the body of the Church. We don't need a revelation to recognize that schism, heresy, and apostasy on the one hand, and Church membership on the other hand, are incompatible. A Church member confesses the faith; a schismatic, heretic, or apostate confesses ideas contrary to the faith.
"Nor must one imagine that the Body of the Church, just because it bears the name of Christ, is made up during the days of its earthly pilgrimage only of members conspicuous for their holiness, or that it consists only of those whom God has predestined to eternal happiness.
It is owing to the Savior's infinite mercy that place is allowed in His Mystical Body here below for those whom, of old, He did not exclude from the banquet.He *then* goes on to say:
For not every sin, however grave it may be, is such as of its own nature to sever a man from the Body of the Church, as does schism or heresy or apostasy." You did not post the immediately preceding (bolded) parts to put the final sentence in context, where Pope Pius XII said that place is allowed in the Body of the Church for those whom Christ Himself did not exclude from the banquet (Mat. 9:11/footnote) and basically, that the Body of the Church includes sinners. Heresy is a sin, a heretic is a sinner.
He then reminds us that, to some degree at least, *all* sin severs man from the Body of the Church - which is true, no? But the sin of schism or heresy or apostasy severs a man from the Body of the Church worse than other sins because of the nature of those particular sins.
Quote from: St. Robert Bellarmine, De Romano Pontifice
it is proven with arguments from authority and from reason that the manifest heretic is "ipso facto" deposed.
[...]
This principle is most certain. The non-Christian cannot in any way be Pope, as Cajetan himself admits (ib. c. 26). The reason for this is that he cannot be head of what he is not a member; now he who is not a Christian is not a member of the Church, and a manifest heretic is not a Christian, as is clearly taught by St. Cyprian (lib. 4, epist. 2), St. Athanasius (Scr. 2 cont. Arian.), St. Augustine (lib. de great. Christ. cap. 20), St. Jerome (contra Lucifer.) and others; therefore the manifest heretic cannot be Pope.
The reason, St. Robert gives, is: "he cannot be head of what he is not a member". Thus, we know by reason itself, that a heretic cannot in any way be Pope: ius divinum naturale.
The problem here is, he *is* pope. Our knowledge of his sins of heresy in no way give us the authority to declare otherwise. Thankfully, God did not grant us either supreme nor various degrees of authority based on what we know. Can you imagine it otherwise?