One of many examples where the Reformed are closer to Catholics than many realize, on the relation of sanctification to justification:
“Whomsoever God justifies, he sanctifies. ‘But ye are sanctified, but ye are justified.’ I Cor 6:6: The Papists calumniate Protestants; they report them to hold that men continuing in sin are justified; whereas all our Protestant writers affirm, that righteousness imputed, for justification, and righteousness inherent, for sanctification, must be inseparably united. Holiness indeed is not the cause of our justification, but it is the attendant; as the heat in the sun is not the cause of its light, but it is the attendant. It is absurd to imagine that God should justify a people, and they should still go on in sin. If God should justify a people and not sanctify them, he would justify a people whom he could not glorify. A holy God cannot lay a sinner in his bosom. The metal is first refined, before the king’s stamp is put upon it; so the soul is first refined with holiness, before God puts the royal stamp of justification upon it.”
Thomas Watson, A Body of Practical Divinity, emphasis mine
That is some strong language, which unfortunately most contemporary Calvinists would hesitate to duplicate, for fear of running afoul of simul iustus et peccator.
Photo: “After the Rain” by Gordon McBryde, p0rg.deviantart.com