There are people who are ill informed about the Ten Commandments and the moral law even though they are Orthodox Christians. We cannot judge them, but only hope that by our good example, they will come to the truth.
I knew a lady who came from a post-communist country, the Ukraine.
Since she spent her childhood under atheistic communism, she was never raised in the Orthodox Church, even though her Greek grandmother did baptize her as an infant. When she came to the USA in her 20s with her mother, they both joined a Greek Orthodox Church, studied catechism for one year, and then they were both Chrismated. Believe it or not, during that catechism class, adultery and fornication were never discussed. I guess the priest thought that everyone understood the Ten Commandments!
Anyway, the poorly catechized Greek lady was married outside of the church by a Justice of the Peace because she did not understand that she should have a Holy Crowning. When her priest told her that she was fornicating because she had not been married in the Orthodox Church, and that her marriage needed to be blessed in the Orthodox Church, at first she sought the blessing of the bishop, but suddenly she changed her mind because she said that her "marriage" was now on the rocks anyway. She was upset when the priest penanced her because of her divorce as she was not married in the Church. Several years later, she was allowed to come to Holy Communion.
Then there was another lady in that same class who was born, raised, and married in the USA, but she also was never taught the Ten Commandments due to our very secular education in the USA. She was baptized into the Greek Orthodox Church and continued to use an IUD for birth control because she never mentioned that to the priest. In addition, she was never told that the primary action of the IUD prevents the implantation of a fertilized ovum by creating a hostile chemical environment in the uterus. Thus the IUD is abortifacient. As she was experiencing several horrific miscarriages every year, she thought it strange, but her doctor did not inform her, nor did she did not associate these miscarriages with the IUD.