The two can not both be correct. God isn't the author of confusion. Calvinism ultimately sprung from a cult that Augustine was once part of, along with Aristotle's philosophy. It's origin isn't scripture, but human philosophy plus gnosticism.
That is true indeed, brother. God is not the author of confusion. However, as we know man is able to confuse using God's words.
Calvinism's foundation is the teaching that alleges it is founded in the five solas, and is known by the acronym, TULIP. This TULIP construct defines humans place in God's plan and God's plan for our placement in his kingdom.
For those for whom Calvinism and TULIP may be unknown or a new topic to encounter here:
Tulip=
Total Depravity, humans are dead in their sins unable to comprehend the divine.
Unconditional Election, God chooses us for his grace, because our totally depraved nature is unable to know God to make that choice ourselves. We do nothing to attain his grace and attention, he chooses us according to his own criteria.
Limited Atonement, this point goes by the teaching that Emmanuel Christ did not die to save all people in the world. His sacrifice was to seal the Elect predestined for the gift of God's grace of Salvation through that sacrifice on the cross.
Irresistible Grace, meaning that for those who are predestined as God's Elect, they are unable to resist the call to his word, grace, and of course, Salvation.
Perseverance of the Saints, also equated with the teaching often conflated with Calvinism while not necessarily so because, Once Saved Always Saved, does not always adhere to the four other TULIP points. Perseverance of the Saints, means when the individual was predestined before the world came to exist to be one of God's elect, they are always that and can never fall from that state. They were his before the womb, and they remain his until they face him in Heaven.
As I had stated prior, these Calvinism points are sustained by scripture.
Total Depravity, from Genesis 2, Romans 5, as two examples.
Unconditional Election, Genesis 8, Jeremiah 17. These scriptures are just two examples of scriptural support for each point. There are more but for brevity I leave it to two.
Limited Atonement, 1 John 5 and Titus 3.
Irresistible Grace, John 6, Romans 8.
Perseverance of the Saints, John 15, Philippians 2,
This does not mean that God agrees with the principles of Calvinism, nor that Emmanuel the Christ was born to deliver what has been encapsulated by man into the Calvinist doctrine.
Rather, it is to show that Calvinism argues its point through scriptures that can be used, perhaps out of context, or misapplied as some would argue, in order to defend the viability of Calvinism as, of God.
To precede what would be a natural query after having posted the above, no, I am not a Calvinist.