Gay marriage or same-sex marriage refers to marriage between two people of the same gender, typically because they are homosexual. It is a controversial subject in many religions and countries. Some countries allow a similar status of "civil union" which is marriage in all but name.
Arguments for gay marriage
If people want to get married, even if they of the same gender, there is no good reason to stop them. Therefore gay marriage should be allowed.
Gay marriage provides stability and benefits to the lives of those involved. For example, if one person is sick, the marriage partner has additional rights when dealing with authorities.
In July 2007, Austin Cline ran a poll on his weblog asking whether atheists should be allowed to marry. Respondents overwhelmingly said that marriage is a civil institution, not a religious one (it should be kept in mind that this poll was posted on an atheist weblog, and therefore the distribution of respondents was certainly skewed). Based on this, Cline drew the obvious conclusion:
- "If religion isn't a good reason to prevent atheists from getting married, how can it be a good reason to prevent gays from getting married?"
Arguments against gay marriage
Both religious and secular arguments have been presented against gay marriage. It is notable, however, that most of the opponents of gay marriage—certainly the most vocal ones—present religious arguments, either alone or in addition to secular arguments. Rarely, if ever, does anyone present secular arguments alone. This leads to the conclusion that opposition to gay marriage is primarily rooted in religious beliefs. Arguments from religious beliefs fail as arguments since there is no evidence to suggest any holy book is true, and places like the United States have separation of church and state.
Contrary to the purpose of marriage
- "[Same sex marriage] also denies the specific primary purpose of marriage: the perpetuation of the human race and the raising of children. "
This is a teleological argument based on the suppose purpose of marriage. However, the assumption that marriage has a particular "purpose" has not been established. Marriage is a human invented concept and only has meaning that we bestow on it.
- "[Heterosexual marriage] naturally tends to create families. On the contrary, same-sex “marriage” is intrinsically sterile. "
This variation of the argument commits the naturalistic fallacy. Just because something occurs in nature, does not in itself make it desirable.
Apologists claim that same sex marriage violates natural law.
- "Marriage is not just any relationship between human beings. It is a relationship rooted in human nature and thus governed by natural law. "
There is no grounds to believe any "natural law" exists, except in the human mind. There is also little agreement as to what natural law entails. It is also difficult to justify any such natural law without committing the naturalistic fallacy. 
- "It is in the child’s best interests that he be raised under the influence of his natural father and mother. This rule is confirmed by the evident difficulties faced by the many children who are orphans or are raised by a single parent, a relative, or a foster parent. "
Research shows that having two parents, either same sex or heterosexual, is about the same for children.
- "On the basis of a remarkably consistent body of research on lesbian and gay parents and their children, the American Psychological Association and other health, professional, and scientific organizations have concluded that there is no scientific evidence that parenting effectiveness is related to parental sexual orientation "
Validates and promotes deviant lifestyles
That assumes homosexuality is a choice, which it is not. Since it is not a choice, it does not matter if this lifestyle is validated or promoted since it will not significantly influence people's behaviour. It's like saying an owl festival would encourage people to become owls, which is absurd.
Devalue traditional marriage
Apologists argue that same sex marriage devalues traditional marriage. 
This is a vague statement: what does the apologist mean by "devalue"? The existing heterosexual marriages can continue in exactly the same way as before. No harm, no foul.
Weaken public morality
Apologists argue that same sex marriage weakens public morality. 
This argument assumes that homosexuality or same sex marriage is immoral, which is not generally accepted. The concept of "public morality" and how it may be "weakened" is vague and arguably meaningless.
Subverts state support for marriage
- "One of the main reasons why the State bestows numerous benefits on marriage is that by its very nature and design, marriage provides the normal conditions for a stable, affectionate, and moral atmosphere that is beneficial to the upbringing of children—all fruit of the mutual affection of the parents. "
This argument is an argument from authority that the purpose of marriage is to raise children. However, the state is not a generally recognised authority on this matter.
The state supports childless marriages. Based on this argument, these couples are exploiting the state by taking benefits and not spending them on children. This is absurd.
If it were necessary to only support child rearing marriages, the state could change regulations so only these families receive state support.
Violates freedom of conscience
- "In every situation where marriage affects society, the State will expect Christians and all people of good will to betray their consciences by condoning, through silence or act, an attack on the natural order and Christian morality. "
Freedom to persecute others is not a generally recognised freedom. Freedom of conscience is not absolute: for instance, it does not extend to owning slaves. Society and governments can limit what is acceptable behaviour and it does not need to defer to freedom of conscience.
Thin end of the wedge
- "same-sex “marriage” serves to validate not only such unions but the whole homosexual lifestyle in all its bisexual and transgender variants. "
- "The reality is that same-sex “marriage” is just another step in the process to erase the boundaries of what constitutes marriage and family. "
This is a thin end of the wedge argument, which is of questionably validity. Event A (same sex marriage) is argued to be undesirable because it would lead to Event B (an undesirable outcome), or at least make it more likely. The problem is that the inevitability or increased likelihood of Event B occurring because of Event A has not been established. Same sex marriage does not automatically make incest, pedophilia or bestiality occur. We can allow same sex marriage but to continue to forbid incest, pedophilia and bestiality.
It offends God
Apologists argue against same sex marriages because it supposedly offends God. 
This assumes God exists, God has a morality in mind, humans could know what God has in mind and humans should obey God. None of this has been established reliably.
Pushes people away from religion
Acceptance of gay marriage has been blamed for the decline of religion in the US. However, while this might explain people changing denominations, it does not explain why people leave religions altogether. 
- "Calling something marriage does not make it marriage. "
- "marriage is between one man and one woman and once you redefine that you lose the essence of marriage itself. "
The meaning of words has changed over time. If a word is used in a particular way or context, that is the meaning of the word. As Wittgenstein argued, "meaning is use". Calling something marriage does, in a sense, make it marriage as long as we have a shared understanding of the usage. You don't necessarily need to agree with the usage to understand it.
It is one thing for religions to try to influence the behaviors of their adherents, but it is presumptuous of them to try to interfere with outsiders lives when it is really none of their business.
There is no evidence that allowing gay marriage causes harm to society. However, people living happily and harmoniously in gay marriage does illustrate how backward some religions are, which is probably why they oppose it.
Gay marriage is currently legal in 21 countries. 
Recently, many counties are moving towards legalization, such as Ireland and Greenland.
Gay marriage is currently a controversial political issue in the United States. It is currently legal in Massachusetts, Vermont, Connecticut, New Hampshire, and Iowa. The District of Columbia, better known as Washington D.C., the capital of the US, allowed same sex marriages in February 2010.
The Catholic church is opposed to allowing gay marriage, which it traditionally regards is "intrinsically disordered" , even for non-Catholics. A senior figure in the Catholic church reacted to the Irish 2015 referendum that supported gay marriage by saying:
- "The church must take account of this reality, but in the sense that it must strengthen its commitment to evangelisation. I think that you cannot just talk of a defeat for Christian principles, but of a defeat for humanity. "
Pope Francis has made some positive statements about recognising, to a limited extent, gay marriage but not introduced any drastic change in policy. 
Church of England
Church of Scotland
The Church of Scotland is moving towards allowing gay ministers who are also in a civil union. 
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- ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 TFP Student Action, 10 Reasons Why Homosexual “Marriage” is Harmful and Must be Opposed
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- ↑ The Young Turks, Rush Limbaugh Blames Gay Marriage For Decline Of Religion, 16 May 2015
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- ↑ 9.0 9.1 
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- The Gay Marriage Debate on ProCon.org
- Catholic bishops use election to warn against marriage equality (Australia)