Presbyterian theology affirms the eternal pre-existence of the Son of God as the second person of the Trinity, entirely consistent with Nicene orthodoxy. The Westminster Confession (Chapter VIII.2) refers to 'the Son of God, the second person of the Trinity, being very and eternal God, of one substance and equal with the Father' taking on human nature. The covenant of redemption (pactum salutis) — a distinctively Westminster theological concept — presupposes the pre-existence of the Son: from eternity, the Father appointed the Son as mediator and the Son accepted this role, before the creation of the world.

The pre-existence of Christ has direct implications for Presbyterian covenant theology: Christ as the 'last Adam' is the eternal Son who undertook to fulfill what the first Adam failed to do — perfect obedience to the covenant of works on behalf of the elect. This grounds the imputation of both Christ's active righteousness and the guilt of sin, both of which require an eternal and fully divine mediator.