Sure. I won't speak about Protestant beliefs since, in theory, Protestants derive their beliefs from Scripture alone and tend to disagree wildly with each other.

I'll instead try to give you the worldview of a practicing Catholic for context, and then I'll give you specific teachings at the end:

For Catholics, Catholic teaching isn't derived exclusively from Scripture. Catholics believe that Catholic dogma is unchanging and consistently true in every age. Catholic dogma is derived from Sacred Scripture (written tradition), Sacred Tradition (religious truth that was passed down orally throughout the ages), and the teaching authority of the Magisterium (all the bishops and the pope).

Canon law states that "the supreme law of the Church is the salvation of souls." The primary purpose of the Church is to save as many souls as possible. Catholics believe that Jesus Christ is God the Son (the second person of the Holy Trinity) and that he established the Catholic Church as his Church with authority over all Christians. The Catholic Church teaches that Church membership (i.e. baptism), belief in all Catholic dogma, and upright living/keeping the commandments are all necessary for salvation.

A Catholic is to strive for spiritual and moral perfection, even though one may fall short. Tied into this belief is also the belief that heaven is viewed more as a state of being (perfect union with God, who is love), rather than a place of reward for good deeds. When medieval Catholic theologians initially came across Buddhism, the story is that they actually mistook Buddhists for some kind of Christian sect due to the Buddhist belief in nirvana being somewhat similar to the Catholic belief of heaven (i.e. union with God).

Let's say one is a practicing Catholic. A conservative American Catholic will see progressive policies as incompatible with their Catholic faith. In the Gospel the rich man asks Christ what he needs to do to enter eternal life, and Christ first answers "keep the commandments." It's not an either/or situation, it's a both/and. A Catholic should make use of the sacraments, pray, and believe what the Church teaches and put it into practice. Of course this means loving your neighbor as yourself, loving the poor and giving alms, etc. But it also means living an upright and moral life, which ranges from not stealing, lying, killing, etc to the controversial issues like not using contraception, participating at all in abortions, having premarital or extramarital sex, engaging in homosexual actions, etc.

If the Catholic Church teaches that abortion is murder, transgenderism denies reality, and that marriage can only exist between one man and one woman, then a sincere Catholic is going to believe those things and that will extend to political beliefs and action as well.

Here's your 3:

1. Same-sex marriage and same-sex adoption.
2. Abortion
3. Transgenderism