John Calvin makes clear baptism is not necessary for salvation:
"How much evil has been caused by the dogma, ill expounded, that baptism is necessary to salvation.
For when the opinion prevails that all are lost who happen not to be dipped in water, our condition becomes worse than that of God's ancient people, as if his grace were more restrained than under the Law.
In that case, Christ will be thought to have come not to fulfil, but to abolish the promises, since the promise, which was then effectual in itself to confer salvation before the eighth day, would not now be effectual without the help of a sign."
- John Calvin, Institutes, Book IV, Ch. 15.