This extract from Abraham Booth comes from A.W. Pink's book The Divine Covenants:
"It is of great importance to the right interpretation of many passages in the O.T., that this particular be well understood and kept in view. Jehovah is very frequently represented as the Lord and God of all the ancient Israelites; even where it is manifest that the generality of them were considered as destitute of internal piety, and many of them as enormously wicked. How, then, could He be called their Lord and their God, in distinction from His relation to Gentiles (whose Creator, Benefactor, and Sovereign He was), except on the ground of the Sinai covenant? He was their Lord as being their Sovereign, whom, by a federal transaction they were bound to obey, in opposition to every political monarch who should at any time presume to govern them by laws of his own. He was their God, as the only Object of holy worship; and whom, by the same National covenant, they had solemnly engaged to serve according to His own rule, in opposition to every Pagan idol.
"But that National relation between Jehovah and Israel being long since dissolved, and the Jew having no prerogative above the Gentile; the nature of the Gospel economy and of the Messiah’s kingdom absolutely forbids our supposing that either Jews or Gentiles are warranted to call the Universal Sovereign their Lord or their God, if they do not yield willing obedience to Him and perform spiritual worship. It is, therefore, either for want of understanding, or of considering the nature, aspect, and influence of the Sinai Constitution, that many persons dream of the New Covenant in great numbers of places where Moses and the Prophets had no thought of it, but had the Convention at Horeb directly in view. It is owing to the same ignorance, or inadvertency, that others argue from various passages in the O.T. for justification before God by their own obedience, and against the final perseverance of real saints.
"Again, as none but real Christians are the subjects of our Lord’s kingdom, neither adults nor infants can be members of the Gospel Church in virtue of an external covenant or a relative holiness. A striking disparity this, between the Jewish and the Christian Church. A barely relative sanctity [that is, a sanctity accruing from belonging to the nation of God’s choice, A.W.P.] supposes its possessors to be the people of God in a merely external sense; such an external people supposes an external covenant, or one that relates to exterior conduct and temporal blessings; and an external covenant supposes an external king. Now an external king is a political sovereign, but such is not our Lord Jesus Christ, nor yet the Divine Father.
"Under the Gospel Dispensation, these peculiarities have no existence. For Christ has not made an external covenant with any people. He is not the king of any particular nation. He dwells not in a temple made with hands. His throne is in the heavenly sanctuary, nor does He afford His visible presence in any place upon earth. The partition—wall between Jews and Gentiles has long been demolished: and, consequently, our divine Sovereign does not stand related to any people or to any person so as to confer a relative sanctity, or to produce an external holiness.
"The covenant made at Sinai having long been obsolete, all its peculiarities are vanished away: among which, relative sanctity [that is, being accounted externally holy, because belonging to the nation separated unto God, A.W.P.] made a conspicuous figure. That National Constitution being abolished, Jehovah’s political sovereignty is at an end. The Covenant which is now in force, and the royal relation of our Lord to the Church, are entirely spiritual. All that external holiness of persons, of places, and of things, which existed under the old economy, is gone for ever; so that if the professors of Christianity do not possess a real, internal sanctity, they have none at all. The National confederation at Sinai is expressly contrasted in Holy Scripture with the new covenant (see Jer. 31:31-34; Heb. 8:7-13), and though the latter manifestly provides for internal holiness, respecting all the covenantees, yet it says not a word about relative sanctity" (Abraham Booth, 1796).