I’ll just point out that there are evangelical protestants who disagree with you and follow what you’ve (mis)stated the Catholic position to be; but suffice it to simply be an example of what others have stated - we can’t generalize protestant beliefs/practices.
The Catholic Catechism states on baptism the following:
1213 Holy Baptism is the basis of the whole Christian life, the gateway to life in the Spirit (vitae spiritualis ianua),4 and the door which gives access to the other sacraments. Through Baptism we are freed from sin and reborn as sons of God; we become members of Christ, are incorporated into the Church and made sharers in her mission: "Baptism is the sacrament of regeneration through water in the word."5
If regeneration, freedom from sin, adoption, and being incorporated into the Church all occur at baptism, then it seems to me that Catholics believe baptism is what makes someone a Christian. How am I misstating the Catholic position? (I’m aware about baptism of desire and baptism of blood, but it seems that this applies to people who explicitly wanted to be baptized but died before having the opportunity.)
Can you name me an actual evangelical Protestant who believes baptism is what makes someone a Christian? It’s been a defining feature of Evangelicalism for its entire existence that a person is joined to Christ the moment he places his faith and trust in him and repents of sin, irregardless of whether this takes place during baptism or on a street corner somewhere.
Yes Presbyterians do practice infant baptism as you said.
And as to baptism not required, from the PCUSA perspective…
“Can a person who is not baptized be saved?”
“In a word, yes; but this by no means diminishes the importance of the sacrament. To insist on baptism as necessary for salvation would be to impinge on the limitless sovereignty of God, one of the essentials of the Reformed theological tradition. At the same time, baptism is an indispensable part of Christian life (Rom. 6:3–4), Christian identity (Gal. 3:27–28), and the church’s mission (Matt. 28:19).”
presbyterianmission.org/story/what-presbyterians-believe-the-sacrament-of-baptism/
PCUSA hasn’t been representative of evangelical Presbyterianism for sometime. But even they deny baptismal regeneration, while also affirming the importance of baptism.
What the Westminster Confession (Presbyterianism’s most important confession of faith) states on baptism is this:
Of Baptism
I. Baptism is a sacrament of the New Testament, ordained by Jesus Christ,[1] not only for the solemn admission of the party baptized into the visible Church;[2] but also to be unto him a sign and seal of the covenant of grace,[3] of his ingrafting into Christ,[4] of regeneration,[5] of remission of sins,[6] and of his giving up unto God, through Jesus Christ, to walk in the newness of life.[7] Which sacrament is, by Christ’s own appointment, to be continued in His Church until the end of the world.[8]
{Cut for space}
IV. Not only those that do actually profess faith in and obedience unto Christ,[11] but also the infants of one, or both, believing parents, are to be baptized.[12]
V. Although it is a great sin to contemn or neglect this ordinance,[13] yet grace and salvation
are not so inseparably annexed unto it, as that no person can be regenerated, or saved, without it:[14] or, that all that are baptized are undoubtedly regenerated.[15]
VI. The efficacy of Baptism is not tied to that moment of time wherein it is administered;[16] yet, notwithstanding, by the right use of this ordinance, the grace promised is not only offered, but really exhibited, and conferred, by the Holy Ghost, to
such (whether of age or infants) as that grace belongs unto, according to the counsel of God’s own will, in His appointed time.[17]
Paragraph 5 points out that while baptism should not be neglected unbaptized people can still be saved and baptized people might not have been regenerated. Paragraph 6 ties baptismal theology to the Calvinistic doctrine of election. Some are predestined to salvation, while others are predestined to damnation. Baptism of infants does not change this.
This is why the Confession can say that the grace promised in baptism is really conferred, eventually (note the first sentence of paragraph 6), to those the grace “belongs unto”. The grace does not belong to those infants or adults who are not among the elect, and so baptism will not be effective.
For those who are among the elect, the grace promised in baptism will be conferred at the moment of regeneration (which doesn’t occur at infancy but in God’s appointed time").
Another Reformed confessional writing, the Heidelberg Catechism states in question 72: “Does this outward washing with water itself wash away sins? Answer: No, only Jesus Christ’s blood and the Holy Spirit cleanse us from all sins.”
In historic Reformed theology, the sacraments only become effective through the faith of the one receiving the sacrament. Question 91 of the Westminster Shorter Catechism states: "
How do the sacraments become effectual means of salvation? Answer: The sacraments become effectual means of salvation, not from any virtue in them or in the one who administers them, but only by the blessing of Christ, and the working of his Spirit in those who by faith receive them."