9 Concurring with these statements, Paul, speaking to the Romans, declares: “Much more they who receive abundance of grace and righteousness for [eternal] life, shall reign by one, Christ Jesus.” It follows from this, that he knew nothing of that Christ who flew away from Jesus; nor did he of the Saviour above, whom they hold to be impassible. For if, in truth, the one suffered, and the other remained incapable of suffering, and the one was born, but the other descended upon him who was born, and left him again, it is not one, but two, that are shown forth.
But that the apostle did know Him as one, both who was born and who suffered, namely Christ Jesus, he again says in the same Epistle: “Do you not know, that so many of us as were baptized in Christ Jesus were baptized in His death? That like as Christ rose from the dead, so should we also walk in newness of life.” But again, showing that Christ did suffer, and was Himself the Son of God, who died for us, and redeemed us with His blood at the time appointed beforehand, he says: “For how is it, that Christ, when we were yet without strength, in due time died for the ungodly?
But God commends His love towards us, in that, while we were yet sinners, Christ died for us. Much more, then, being now justified by His blood, we shall be saved from wrath through Him. For if, when we were enemies, we were reconciled to God by the death of His Son; much more, being reconciled, we shall be saved by His life.” He declares in the plainest manner, that the same Being who was laid hold of, and underwent suffering, and shed His blood for us, was both Christ and the Son of God, who did also rise again, and was taken up into heaven, as he himself [Paul] says: “But at the same time, [it, is] Christ [that] died, yea rather, that is risen again, who is even at the right hand of God.” And again, “Knowing that Christ, rising from the dead, dies no more:” for, as himself foreseeing, through the Spirit, the subdivisions of evil teachers [with regard to the Lord's person], and being desirous of cutting away from them all occasion of cavil, he says what has been already stated, [and also declares:] “But if the Spirit of Him that raised up Jesus from the dead dwell in you, He that raised up Christ from the dead shall also quicken your mortal bodies.” This he does not utter to those alone who wish to hear: Do not err, [he says to all:] Jesus Christ, the Son of God, is one and the same, who did by suffering reconcile us to God, and rose from the dead; who is at the right hand of the Father, and perfect in all things; “who, when He was buffeted, struck not in return; who, when He suffered, threatened not;” and when He underwent tyranny, He prayed His Father that He would forgive those who had crucified Him. For He did Himself truly bring in salvation: since He is Himself the Word of God, Himself the Only-begotten of the Father, Christ Jesus our Lord.
Source: Adversus haereses (New Advent)