Holiness—the nature of God cannot rationally be conceived without it

Though the power of God be the first rational conclusion, drawn from the sight of his works, wisdom the next, from the order and connexion of his works, purity must result from the beauty of his works. … Though we conceive him infinite in Majesty, infinite in essence, eternal in duration, mighty in power, and wise and immutable in his counsels; merciful in his proceedings with men, and whatsoever other perfections may dignify so sovereign a Being.

If any, holiness hath an excellency above his other perfections

There are some attributes of God we prefer, because of our interest in them, and the relation they bear to us: as we esteem his goodness before his power, and his mercy whereby he relieves us, before his justice whereby he punisheth us; as there are some we more delight in, because of the goodness we receive by them; so there are some that God delights to honor, because of their excellency.

None is sounded out so, loftily, with such solemnity, and so frequently by angels that stand before his throne, as holiness (Is 6:3). … He singles it out to swear by (Psalm 89:35).

—Stephen Charnock
The Existence and Attributes of God, vol. 2 (Robert Carter & Brothers, 1853), 111–112.