And reading is your friend, you can't just Google "Church Gay Lawsuit" and pick a few, you have to actually READ:
Iowa' Gortz Haus lawsuit (Mennonite): They are preemptively suing out of fear, they have never been forced or asked. They are just afraid. Fear is not a lawsuit. Also, its not a church but a Bed and Breakfast that was a former church. So, again not a religious place just religious people who want to have a public business that is only open to the public types of people they like. http://christiannews.net/2013/10/13/mennonite-wedding-venue-files-counter-suit-to-avoid-being-forced-to-host-same-sex-weddings/
New Jersey's United Methodist Church in Orange Grove: this one is dicey and I personally would come down on the side of the church but they set themselves up. They let others not of their faith (non-christians) and even counter to their faith (Jewish) rent the facility. So to suddenly say no to a group on religious grounds is disingenuous. They even booked a non-christian wedding after they said no to the gays. So, why are they not applying this "faith" to everyone? That was the issue and nothing else. If they really have Faith then why is not applied to everyone? You can't pick and choose. Either you are and you have rules or you are not and you don't. http://www.lifesitenews.com/news/judge-rules-christian-facility-cannot-ban-same-sex-civil-union-ceremony-on/
Emmanuel Temple House of Praise and Lighthouse Outreach Center Assembly of God: This one argues against you! The law has protections to PREVENT them from being forced, and they still sued. Again they were never asked they just don't want gays getting married. http://www.religioustolerance.org/hommarrhi11.htm
The issue with a continuum is where does it start and where does it stop? Ok, only Marriage services? Ok, well this law goes MUCH further than that. I could walk into a Pharmacy and be denied and force to leave. I could walk into ANY kind of store and be denied service. You want to argue on a continuum, then who makes the list, who enforces it, and what if a facility offers multiple services? If one is "protected" and the other is not which rules apply? You could write it but realistically it would be a nightmare to maintain, enforce, etc. It will become a political game and the winner will be the people with more money, it won't be based on such lovely ideas as morals, rights, wrongs, and fair. For evidence see the tax code and nearly every other "continuum" system we have.
Again you seek to narrow history. Hate to tell you, life and history and people existed BEFORE the USA. Just because they have what you believe to be easy explications and reasons for why they did things does not make it something you can exclude from history or "tradition" just because we have found another way to solve them. They are part of our history and our traditions. In South America they have plural men to one woman in some ethnic groups. Same in African nations. In Arab nations they still have multiple wives. There are many people here from Arab nations shall we follow their traditions? You left out the Greeks, the Egyptians, the Romans, the Huns, and Aboriginal people. Again you focus on a few European groups that follow you beliefs. Does not make it plural or traditional, just what you are most familiar with.
Marriage is a word, it is defined by the users. Religious groups do not have a trademark on the term. So it is defined and used as desired by the plurality of the people. Don't like it? Create a new term, trademark it, and license it only to people who agree with you. The politicians are lazy, but in this case they were right. They used the colloquial term used by most all no matter if they got a religious or non-religious contract.
Also, you say "many countries". Can you list them out? I know of few that went that route that were not already that way. In fact I know of none that have not started the process of full Marriage due to the difference in application of the laws, but I am sure I have not check them all.