In the genesis story, God is said to have made man ‘in his own image’. When God made us in his own image he made us special. And so, humans are sacred and God loves us so we have no right to take a life, even if the foetus is disabled.
The Sanctity of Life is an argument that a Christian could use to argue against abortion. The Sanctity of Life is the belief that all life is sacred and belongs to God. God is responsible for all creation and only he can give or take life. Therefore humans have no right to take life and so abortion is wrong.
Catholics use Aquinas’ Natural Law theory in order to solve questions on modern issues. One of the absolute primary precepts is preserving life. Abortion goes against this and so it is wrong. However the doctrine of double effect allows for an operation in an ectopic pregnancy that has the side effect of an abortion. Catholics therefore believe that abortion needs to be avoided in all situations and adoption is a much better option.
Situation ethics is a branch of Christian ethics which is relativist, the only absolute is love. Situation ethics says that you should always do the most loving thing. In some situations an abortion may be the most loving thing to do. For example, if a woman has fallen pregnant from rape or if the child would be severely disabled and have a bad quality of life, the most loving thing may be to allow an abortion.
The Church of England has a more relativist view also. They believe that abortion should always be avoided as much as possible. However in some situations and circumstances they may say that abortion could be the lesser of two evils. For example, if the child would not have a good quality of life, or could not be cared for well, or if the pregnancy would kill the mother then an abortion could save further suffering.
In conclusion, different branches of Christianity have different views of whether abortion is right or wrong. Some Christians believe in the divine command theory and that abortion is wrong because it goes against the Ten Commandments. Some condemn it because of the sanctity of life. Catholics who use the Natural Law theory also believe it is wrong. However situation ethics and the Church of England have a more relativist approach and believe that in some situations abortion is acceptable.