Evangelical Christians have enormous political power. That's why the last three appointees to the Supreme Court were vetted by pro-Life organizations and Roe v. Wade is in imminent danger.
Evangelicals Protestantism is the biggest religious category in the country (25%), yet no Supreme Court justice is Evangelical. By contrast, 6-7 are Catholic (21%) and 2 are Jewish (2%). That doesn't seem like enormous political power to me.
The Supreme Court includes a number of conservative Catholics, appointed by Presidents who were either evangelical Christian (Alito/Bush) or closely allied with them (Kavanaugh/Trump, Barrett/Trump), who tend to take positions on policies that are similar to that of evangelical Christians.
Amy Coney Barrett may be Catholic, but she was heavily favored by evangelicals, with specific interest in overturning Roe v. Wade.
Indeed, they are a large voting base of an alliance of religious conservatives (along with Mormons, conservative Catholics, etc.) that is hyperfocused on that one issue, and so seemingly having some success on it.
But it's not like Amy Coney Barrett is barely Catholic. She's been heavily involved in the church her whole life, and her career has been centered around a deeply Catholic university. She only represents Evangelicals in situations where their belief overlaps with those of the Catholic church.
Barrett is both deeply Catholic and part of an organization (https://en.wikipedia.org/wiki/People_of_Praise) that features aspects typically more in line with American evangelical Protestantism. The Catholic Church can be a surprisingly diverse group theologically; American bishops are frequently feuding with the Pope over issues like the death penalty and abortion.
American evangelicals didn't get in line behind Barrett and Kavanaugh on account of their Catholicism.
Have you ever seen one of those art pieces where when you look at it from the front it looks like a jumbled mess of shapes, but when you walk around it, your perspective shifts to reveal a meaningful message or image?
Imagine if rather than gaining its independence from the UK, the USA instead of becoming its own independent country, was still called the United States of America, but over time, in practice it had become totally servile, dependent on, psychologically submissive and subjugated to the British aristocracy that rules the UK and Americans worshipped them as demigods.
And yet, abortions continue to be legal everywhere. It's almost as if, the supreme court is there to just rubber stamp what the elite class of our country already dictates.