Let me briefly try to explain the reasons for taking this position, point by point. The unity of man and woman is seen, by the Bible, as the proper unit for the human family. Homosexual and lesbian relationships are thus not permissible for Christian people. God has ordained that the act of sexual intimacy is to be used within marriage for both pleasure and procreation, the emphasis being on within the marriage. The human life is sacred.
Human beings have rights, including the right to life.
These 'ethics' are generally accepted. On that basis I would say that if in-vitro fertilisation is to be a process where the embryo is treated in an ethical and moral way, then each embryo that is created in the laboratory should be implanted in the woman's uterus. None should be disposed of, frozen, or used for clinical testing. These things deny the embryo the basic human right to life under God. I realise that this probably raises more questions than it answers, so please feel free to submit follow-up questions.