Esdra - thank you for bringing this question up. I appreciate your honesty and your graceousness in giving us the opportunity to clarify who we believe we are and what we believe that may be different from other denominations. It shows great respect to allow a person or a group to define themselves, rather than make assumptions about how the outside should define them. I greatly appreciate the respectful attitude you have shown.
orthodox - of, pertaining to, or conforming to the approved form of any doctrine, philosophy, ideology, etc. (dictionary.com).
According to this definition of orthodoxy, we would consider ourselves orthodox as a church denomination. The Seventh-day Adventist Church has established a set of agreed upon doctrines, which have remained generally consistent and which every local Adventist church worldwide typically holds to and functions from. In this way, we are orthodox, because we agree upon an orthodox theology, philosophy, ideology etc. within our community. Now, if by orthodox you mean conforming to every point of theology, philosophy, ideology, etc. which other Protestant Christian denominations hold, than no we are not orthodox. However, although we do differ in a few points of theology which does change our overall worldview, we also are a lot closer in theology with other Christians than some would like to acknowledge. Truthfully, there is only one doctrine unique to the Seventh-day Adventist theology. All our other docrtines we share with other Christians. We may interpret the doctrines slightly differently, but at the core, they are the same. If you'd like a comprehensive explanation with textual support for each doctrine, you can find it on the official website of the Seventh-day Adventist Church. The web address is www . adventist . org / beliefs (btw, there are no spaces in that address, I just don't have clearance to post links yet and the computer automatically makes it a link).
As far as how other groups see Adventists, that happens for a combination of reasons. Some have simply never heard of Adventists, others have had bad experiences with individuals that claim to be Adventists, and still others have only seen the few times former Adventist individuals caused trouble in the media. There have been a few cult groups that departed from the Adventist Church, but they were not claimed by the church, nor did they want to be. The attitudes of those individuals were hostile toward Adventists because of their own issues. The Adventist Church as a whole is considered a denomination of protestant Christians for all legal purposes. Some churches take issue with us because of our history too. The Advent Movement happened in the 1800s and included individuals from many different denominational groups. The group that became the Seventh-day Adventists were primarily from Methodist roots, but they did not organize themselves until the 1860s (approximately 20 or so years after the movement began), because it was the organized churches that they felt had become stagnant in doctrine and oppressive of people who desired to study Scripture for themselves. So in an effort to stay open-minded and motivated to study the Bible and derive theology directly from Scripture, they resisted organization or a creed. To this day, although the Adventist Church has become organized and has put forth an official statement of beliefs, it has continued to encourage personal Bible study and involvement within the faith community, in an effort to remain open to God's leading. This philosophy of resisting becoming too established in theology and practice has made some others question our orthodoxy. And when Adventists have come in contact with hostile individuals who question our faith, it is only human to desire to retreat from such sources of conflict. In my opinion, this retreat from the rest of the Christian world to protect ourselves has been a downfall for our church which some are very enthusiastically trying to correct now. But the retreating is not because of cult-like beliefs or behaviors, but rather because of fear of conflict.
If you would like to see more information, there are resources to research the history of our church at the same website I referenced for our beliefs. I would also strongly encourage you, if you're interested, to go ahead and visit an Adventist Church or even a couple different Adventist Churches and make your own judgements.
The characterization of cults usually is a dangerous one in which you're stuck once you get into it and it requires you to behave in extreme ways that would endanger you and isolate you from others. Although our philosophy and a few doctrines may be slightly different, we are Christians who love Jesus and want to treat people well, so we won't ask you to endanger yourself or others by associating with us and you are free to choose what you believe and when you will come and go. Adventists function as anyone else within our modern world and we're not intending to harm anyone.