Westminster Larger Catechism

Q80

Can true believers be infallibly assured that they are in the estate of grace, and that they shall persevere therein unto salvation?

Such as truly believe in Christ, and endeavour to walk in all good conscience before him,349 may, without extraordinary revelation, by faith grounded upon the truth of God’s promises, and by the Spirit enabling them to discern in themselves those graces to which the promises of life are made,350 and bearing witness with their spirits that they are the children of God,351 be infallibly assured that they are in the estate of grace, and shall persevere therein unto salvation.352
Doctrine