I was raised Christian and this is what really struck me when I was rediscovering religion, how much Christians have shifted their morality to keep up with the secular world. It's a loosing game. Good morality is never popular, secular society is never going to accept it. What first attracted me to Islam as a teenager, before I knew anything about it, was how dedicated Muslims are to the faith. They still follow the exact same rules given in the Quran 1400 years ago, and adapt their understanding of right and wrong to the book; Christians adapt the book to their secular/worldly understanding of right and wrong. The Bible specifically gives men authority over women, mandates sex segregation and modesty but that doesn't sit well with the secular world so you see women preachers and pastors, unrelated men and women sitting next to one another in the pews, women in blouses and trousers where you can see their body. I go to a mosque and I see men and women separated, as the Quran, the Bible and Jewish Torah commanded. A church will only allow a man to have one wife, even though polygamy is the norm in the Bible, in Islam I am entitled to have 4 wives and nobody can ever take that right away from me etc etc.
Of course, these aren't the only things that attracted me to Islam. I felt that it answered the multitude of questions that Christianity left me with in a much more logical way, that the Islamic Jesus and Mary seemed much more true than the gospel accounts written decades after their death by John, Mark, Luke and Matthew and so much more. However I don't want get into an argument about the narrative and doctrinal differences, I just wanted to ask Christians, what do you think about the adoption of modern secular "values" by most churches?
The Bible is not exactly the Christian equivalent of the Qu'ran, though many Christians make it out to be that. It is not meant to be this static, final, all-compassing, infallible, inerrant, revelation from God. It is written by fallible men who were inspired by God (2 Timothy 3:16's most accurate translation is "All scripture is INSPIRED by God and is also useful for teaching, teaching, for reproof, for correction, and for training in righteousness"), and is a collection of poems, letters, biographies, songs, and apocalyptic literature. The authors of the Bible were men who were inspired by God to write what they did, I do not believe that Paul, in his wildest dreams, would have thought that Christians are still reading his letters to this day, as scripture no less, almost two-thousand years later.
Due to this, and the fact that sometimes teachings appear to contradict, scripture is not meant to be read like a book of teachings where all is equal. There is a story recorded in the Talmuds about two Rabbinical schools, a Roman centurion came to the first school and demanded "Teach me your Torah (the Law) while I stand here on one foot." The rabbi in charge hew him out without saying anything. So he went across town and said the same thing to the other school. The rabbi there said to him "Love God with your whole being and Love your neighbor as yourself. The rest is commentary." THEN he threw him out. The latter is the teachings that Jesus and Paul affirmed in their teachings. When Jesus is asked "What is the greatest command?", he's essentially being asked the same question the centurion is asking those rabbis. Christ answers "'Love the Lord your God with all your heart, with all your soul, and with all your mind.' The second is like it, 'love your neighbor as yourself'. All of the law and the prophets hang on those two commandments." Paul, after building an argument in Romans about law, grace, and sin says "Owe no one anything, except to love one another; for the one who loves another has fulfilled the law. The commandments, 'You shall not commit adultery; You shall not murder; You shall not steal; You shall not covet'; and any other commandment, are summed up in this word, 'Love your neighbor as yourself.' Love does no wrong to a neighbor; therefore, love is the fulfilling of the law" is saying the same thing, if not kind of explaining it as a Jew to his partially Gentile audience. Everyone agreed the greatest commandment was Love the Lord your God, and how you loved God (besides the laws directly against God: idolatry, blasphemy, and apostasy) was by keeping his commandments, and what Jesus and Paul are saying is that you love God by loving your neighbor as yourself.
ALL of the law and the prophets hang on these two commandments.
That doesn't mean that the teachings found in scripture outside of those are entirely meaningless, it means that either are unloving acts (all sin is inherently unloving act and produces bad fruit) or served a specific purpose for a specific time. When scripture says that women are not permitted to teach men or the sex segregated in worship (not found or referenced in the Bible), it is likely that that was a commandment for a specific purpose and a specific reason, and we can see evidence in scripture when the Jewish people and Christian council changed things. For the Hebrews, it was Eunichs, compare Duet. 23:1-3 to Isaiah 56:3-8, Eunichs are excluded to demonstrate God's holiness, but later that command is no longer necessary to accomplish that purpose and becomes obsolete. The early Christian church, it was circumcision. The only scriptures the church had were the Jewish scriptures which commanded circumcision as a sign of allegiance to God, and there was probably less wriggle room in scripture than this. The issue was over whether or not gentiles could become Christians without first being circumcised. The Gentiles in question knew two things: they trusted Jesus and didn't want to take a knife to their manhood. Even Peter and Paul had a public confrontation about this (Gal 2:11-14). The church decided was that it was best for them to not burden them with the requirement because the purpose was no longer needed, and it was following the rules for the sake of the rules.
That is something that Christ consistently challenges in His teachings: following the rules for the sake of the rules. Jesus repeatedly teaches and says that the purpose and principal (love) is more important than the letter of the law. That's the entire purpose of the Sermon on the Mount, and over and over again in the rest of the gospels Jesus reiterates that God is more interesting the the underlying principles than rules themselves. He even takes it a bit further and says the principle of the law actually holds us to a higher standard and requires a larger commitment. That is why all of the things you have brought up have happened or are happening in the Church. God's standards have never changed, though what they have looked like have changed.