The Supreme Court has endorsed the right of Americans to marry whom they choose, regardless of the gender of the spouse. What implications does this have for persons with religious or other objections to gay marriage?
Consider first the role of a clerk in the governmental office that issues marriage licenses. The function of that official is to ascertain whether the couple applying for the license satisfies the legal requirements of age, residency, payment of the fee (if any), etc. This official does not have the right to deny a license for any private reason, such as whether the marriage is inter-racial, inter-religious, non-religious, gay, or the official finds the couple personally unattractive. The official can do the job as prescribed by law, or resign.
The position of a religious group is entirely different. Each such group can decide for itself, according to its own rules, which marriages its leaders can officiate at, and whom it will consider as members. Some religious groups will welcome gays and officiate in gay marriages, others will not. The diversity of views on this, as on many other religious and moral questions, is what our religious liberty is all about.
The real issue for conservative religious groups is cultural, moral, and doctrinal. As gay couples start to become a normal part of American life, it becomes more difficult to exclude them. It may be that some religious groups will find it difficult to stay together because of this issue. But that goes to the exercise of the religious liberty of the individuals involved.
There is no collision between religious liberty and gay marriage. Views on gay marriage have been evolving, and will continue to evolve.