Jesus had the nature of God and took upon Himself the nature of a man. How is that not two natures?
I disagree with RCS and I also disagree with you on the natures.
You would have to prove it from the Bible, and that's not possible, since it teaches He had one nature.
Here is everything the Bible teaches about who Jesus is...
Who Died On The Cross?
"The divine nature isn’t capable of experiencing death" - Calvinist theologian R.C. Sproul
The god of Calvinism is a false god, for they emphatically deny that God died for your sins, and that He has come in the flesh in the person of Jesus Christ (2 John 1:7).
"And without controversy great is the mystery of godliness: God was manifest in the flesh, justified in the Spirit, seen of angels, preached unto the Gentiles, believed on in the world, received up into glory." 1 Tim 3:16
God was made known (revealed) to us through the person of Jesus Christ. It is that person whom we must define as the Bible defines Him. Jesus is the revelation of God to man. He is God in the flesh.
"What was from the beginning, what we have heard, what we have seen with our eyes, what we have looked at and touched with our hands, concerning the Word of Life-- and the life was manifested, and we have seen and testify and proclaim to you the eternal life, which was with the Father and was manifested to us" 1 John 1:1-2
John tells us that the person that has been manifested (made known; revealed) was "with the Father". John is telling us that the person being made known is eternal. He was "with the Father" BEFORE being "manifested" (revealed; made known) to us. He is not a "new" person, or an "added" person, but God Himself in the flesh.
"But when the fullness of the time came, God sent forth His Son, born of a woman, born under the Law" Gal 4:4
"God sent forth". Paul tells us that the Son was sent, which indicates that He was with the Father BEFORE having been sent. The PERSON who was sent is God the Son. This is the PERSON who is manifested (made known; revealed) to us in the flesh.
"...who, although He existed in the form of God, did not regard equality with God a thing to be grasped, but emptied Himself, taking the form of a bond-servant, and being made in the likeness of men." Phil 2:6-7
As already noted, Jesus existed as God, that is, His PERSON is God, who took on the "form" (external appearance) of a bond-servant , and appeared in the "likeness" (image; resemblance) of men. Jesus is God in the flesh. That is His PERSON - His IDENTITY.
"For what the Law could not do, weak as it was through the flesh, God did: sending His own Son in the likeness of sinful flesh and as an offering for sin, He condemned sin in the flesh" Rom 8:3
Paul writes concerning the PERSON who was "sent". It is the Son, who was sent. The PERSON that came here, was "sent". He was "with the Father". And He came in the "likeness" (image; resemblance) of sinful flesh. He had no sin, yet His flesh was "like" (image; resemblance) that of sinful flesh.
"And the Word became flesh, and dwelt among us, and we saw His glory, glory as of the only begotten from the Father, full of grace and truth." John 1:14
John explains to us that the "Word" (who is God) "became flesh". There is nothing spoken here (or anywhere) that Jesus became a soul, or another "person", but that the PERSON (who is God) became flesh. The divine nature became flesh. Not "two natures", but One nature - God in the flesh.
"Jesus said to him, "Have I been so long with you, and yet you have not come to know Me, Philip? He who has seen Me has seen the Father; how can you say, 'Show us the Father'?" John 14:9
Jesus and the Father are One. The Father is God. Jesus is God in the flesh. Jesus said that to know Him is to know God. He did not say that to know Him is to know another person who was "added" to God.
"Being found in appearance as a man, He humbled Himself by becoming obedient to the point of death, even death on a cross." Phil 2:8
Paul makes it clear that God came in "appearance as a man". Paul says that God is the One who humbled Himself to the point of death. He does not say that an "added" person died, but that God died on the cross.
"Therefore, since the children share in flesh and blood, He Himself likewise also partook of the same, that through death He might render powerless him who had the power of death, that is, the devil" Heb 2:14
God took on "flesh and blood". He did not "add" another soul/spirit, mind, will, person, or identity. He is God in the flesh.
"Wherefore when he cometh into the world, he saith, Sacrifice and offering thou wouldest not, but a body hast thou prepared me" Heb 10:5
Again, we see that God came into the world and lived in a "body" that was prepared for Him. Nothing stated about a soul/spirit, mind, will, identity, or distinct person being "added" to this body.
"in these last days has spoken to us in His Son, whom He appointed heir of all things, through whom also He made the world. And He is the radiance of His glory and the exact representation of His nature, and upholds all things by the word of His power When He had made purification of sins, He sat down at the right hand of the Majesty on high" Heb 1:2-3
His nature is that of God. One nature, one mind, one Soul/Spirit, One PERSON, One identity - Jesus is God in the flesh.
"Hereby know ye the Spirit of God: Every spirit that confesseth that Jesus Christ is come in the flesh is of God" 1 John 4:2
The PERSON of Jesus Christ "CAME". He was with the Father and He CAME. He is not an "addition" to God, but God in a body prepared for Him, in the likeness of sinful flesh, the appearance of a man, that is flesh and blood, and the exact representation of God's nature.
The "creed" makers have manufactured a false Jesus, that is NOT God come in the flesh. They have a spirit that denies that Jesus has come in the flesh. They have no biblical evidence to support their two nature, double-minded, double-soul/spirit, double-identity Jesus.
I have laid out nearly every verse that explains who Jesus is regarding His true identity. They (Calvinists/Reformers) have nothing, because nothing to support their false Jesus exists.
It has already been shown that it is indeed God who became a man
God tasted death
"But we see Jesus, who was made a little lower than the angels for the suffering of death, crowned with glory and honour; that he by the grace of God should taste death for every man." Heb 2:9
Jesus (God in the flesh) was "made" lower than the angels. This verse clearly shows it is the same PERSON who was "made" lower. Not a new person, but the SAME PERSON who was "made" lower, by becoming a man, who suffered and experienced death for EVERY man (not just the "elect").
In order for God to be the perfect sacrifice for ALL men, He had to become like man, and to suffer as a man, in the weakness of human flesh.
"In the days of His flesh, He offered up both prayers and supplications with loud crying and tears to the One able to save Him from death, and He was heard because of His piety. Although He was a Son, He learned obedience from the things which He suffered." Heb 5:7-8
The writer of Hebrews points out that God, for a time, suffered in the flesh. It was HIS FLESH, not the flesh of an "added" person, but God in the flesh. This period of time were the days of "His flesh". God became a man, and learned what it was like to be in the flesh, through that which He suffered.
In order for God to become a man, He was born into this world as are all men, by having a body that grew in the womb of a woman.
"Behold, a virgin shall be with child, and shall bring forth a son, and they shall call his name Emmanuel, which being interpreted is, God with us." Matthew 1:23
Again, Jesus is God in the flesh. He came in a body prepared for Him Hebrews 10:5, born into this world of a virgin, being sent by God Himself Gal 4:4, in the likeness of sinful flesh Rom 8:3, yet without sin Heb 4:15. In His body, in the days of His flesh, lower than the angels, He learned and grew in wisdom like any man.
"And Jesus increased in wisdom and stature, and in favour with God and man." Luke 2:52
This is where the false teachers and creed-makers abandon all wisdom and understanding and attempt to recreate Jesus into a second distinct individual, not understanding what Paul says concerning God's ability to be "fashioned as a man who humbled Himself".
"Let this mind be in you, which was also in Christ Jesus: Who, being in the form of God, thought it not robbery to be equal with God: But made himself of no reputation, and took upon him the form of a servant, and was made in the likeness of men: And being found in fashion as a man, he humbled himself, and became obedient unto death, even the death of the cross." Phil 2:5-8
When Jesus "made Himself" a servant, having also been "made" in the likeness of men, and fashioned (appearance) as a man, He abandoned (voided) His reputation as God, and as a man humbled Himself unto death.
When Jesus came into this world, He was conceived of the Holy Spirit (God), and took on human flesh. As a human he experienced hunger, pain, weariness, and death. He submitted Himself to His Father's will at all times. Not out of reluctance, but because His will was to do the will of the Father.
Like all men, Jesus had a brain, heart, lungs, etc. Unlike other men, Jesus was God in the flesh. From the moment of conception Jesus was one Spirit with the Father, and whatever the Father revealed to the child or the man Christ Jesus, was not tainted by the wisdom of this world. All revelation that Jesus received came directly from the Father. Jesus was never a "natural man".
"But as it is written, Eye hath not seen, nor ear heard, neither have entered into the heart of man, the things which God hath prepared for them that love him. But God hath revealed them unto us by his Spirit: for the Spirit searcheth all things, yea, the deep things of God. For what man knoweth the things of a man, save the spirit of man which is in him? even so the things of God knoweth no man, but the Spirit of God. Now we have received, not the spirit of the world, but the spirit which is of God; that we might know the things that are freely given to us of God. Which things also we speak, not in the words which man's wisdom teacheth, but which the Holy Ghost teacheth; comparing spiritual things with spiritual. But the natural man receiveth not the things of the Spirit of God: for they are foolishness unto him: neither can he know them, because they are spiritually discerned. But he that is spiritual judgeth all things, yet he himself is judged of no man. For who hath known the mind of the Lord, that he may instruct him? but we have the mind of Christ." 1 Cor 2:9-16
This destroys the false teaching of Calvinism that Jesus has "two natures", two minds, two wills, and two distinct individual identities. He is God in human flesh that died on the cross for your sins, was buried and raised on the third day.