I do have a sexual preference towards some "races", which is purely circumstantial and I am sure it would drastically change if I moved to a country with different demographics, but if he is the one that clicks for me then he is the one.

Now in terms of religion, yeah that can be a little tougher to overcome.

Thankfully, all religions have (what some people negatively refer to as) "lukewarm" believers that are level-headed.

I think religion can spoil the relationship especially a gay relationship. Because a few dominant religions have brainwashed the entire population that being gay is unnatural. So a lot of people are confused about their identity and cannot fully commit to it.

"religions have brainwashed the entire population that being gay is unnatural"
I believe a proper term would be "religions have brainwashed the entire population that being gay is WRONG"
While I am gay and I don't believe it's wrong, I do believe that being gay is still unnatural (in the literal sense of the word)

I think religion can spoil the relationship especially a gay relationship. Because a few dominant religions have brainwashed the entire population that being gay is unnatural. So a lot of people are confused about their identity and cannot fully commit to it.

Do you think that "race" or religion can ruin a relationship?

I think we need to focus the question a bit:  "Can difference in race or religion ruin a relationship?"  It can; it depends on the people involved.

As for "race," different ethnicities have different levels of privilege in different societies.  If one person in the relationship is of a privileged race, and the other is in a discriminated-against race, it's possible that one or both parties won't understand the experience of the other–or not be perceived as understanding.  This can cause problems in a relationship.

As for religion, most countries (but certainly not all) are tolerant of religious differences.  If the practice of a religion is very important to one party, and not to the other, things can work as long as there's mutual respect.

All of this assumes that a relationship has been formed.  Some people will have a "going-in position" that they could not be in relationship with someone of a particular race or religious practice (or non-practice).  That would filter out problems very early on, although if attraction develops after a casual hookup, people may need to revisit their initial judgments.

At the risk of going off-topic, it's not unlike a relationship between serodiscordant parties (one HIV+ and one HIV-).  Quite often, an HIV+ person will assume that the HIV- party can't fully understand what it's like to be HIV+, and that can become a problem.  This is becoming less of an issue as HIV treatment advances.  (If you want to address the HIV+/- situation, I suggest starting a new forum topic on that, leaving this thread to the race/religion question.)

As far as race is concerned I don't see any problem, only if there are some racist tendencies in the family or social cycle of the couple. But it is up to the couple to reconcile any differences.

So it's down to being a strong couple and having the balls to tell the rest of the world to just Fuck Off and leave you alone.