Here is one example of Calvin contradicting himself, and contradicting Scripture at the same time.
Calvin’s commentary on John 3:16 (Bible Hub): SCRIPTURAL
16. For God so loved the world. Christ opens up the first cause, and, as it were, the source of our salvation, and he does so, that no doubt may remain; for our minds cannot find calm repose, until we arrive at the unmerited love of God. As the whole matter of our salvation must not be sought any where else than in Christ, so we must see whence Christ came to us, and why he was offered to be our Savior. Both points are distinctly stated to us: namely, that faith in Christ brings life to all, and that Christ brought life, because the Heavenly Father loves the human race, and wishes that they should not perish...
That whosoever believeth on him may not perish. It is a remarkable commendation of faith, that it frees us from everlasting destruction. For he intended expressly to state that, though we appear to have been born to death, undoubted deliverance is offered to us by the faith of Christ; and, therefore, that we ought not to fear death, which otherwise hangs over us. And he has employed the universal term whosoever, both to invite all indiscriminately to partake of life, and to cut off every excuse from unbelievers. Such is also the import of the term World, which he formerly used; for though nothing will be found in the world that is worthy of the favor of God, yet he shows himself to be reconciled to the whole world, when he invites all men without exception to the faith of Christ, which is nothing else than an entrance into life.
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CONTRADICTED IN CALVIN'S INSTITUTES: UNSCRIPTURAL
“We say, then, that Scripture clearly proves this much, that God by his eternal and immutable counsel determined once for all those whom it was his pleasure one day to admit to salvation, and those whom, on the other hand, it was his pleasure to doom to destruction. We maintain that this counsel, as regards the elect, is founded on his free mercy, without any respect to human worth, while those whom he dooms to destruction are excluded from access to life by a just and blameless, but at the same time incomprehensible judgment.” Institutes III. 21.7.
So either John Calvin was a very dishonest theologian, or he assumed nobody would catch him in his contradictions. And this is just one example. And Calvinists try to dodge all around this to claim that Calvin did not believe in Unlimited Atonement.