It hurts me to describe our culture by (culture of the rear end).
I have been living in UK for 10 year and I work her as medical doctor I have higher Qualifications than you. You are free to chose the country you like to live in, free to chose the religions you like, the women you want to mary but you can not dictate what other people's choice or describe it as culture of rear end.
I have seen how the western people live even as medical doctor I have seen much of thier life than you have. Regarding your point of view that religions are man made this is your point of view and there are millions other share your point of view but also there are also millions who beleive in God (Allah) and as you live your life they also live thier life. (lakom denakom wa lya dean).
Second religions start with beleive in God if you do not beleive in God so you do not need religion so you should not suggest rework for islam I understand that no body has force you to be religious. also I understand that it is not muslim people who make women mensturate or give birth to child or have estrogen hormone or have postpartum (nifas) rest peroid.
I want to ask you what is the propability of DNA from cell to undergo random rearrangment to creat women instead of man from Zygot cell. Actually this has been calculated and it show no natural force could do that. I beleive in God who make DNA and from simple cell connected to each other to form thinking human been with view and opinion if you look is this came by chance?
Regarding the much injustice in the world this is people interacting with each other what you think is injustice is justice in the other people's eye. What you think is bad in your view is right in view of other people. That is why people can live and make living. Some make gun and some make food. Some are presidents and some poor. All are living and you might find the farmer more comfortable and happy than the president. Religion simply massage from God to make us understand that.