No. They often try and appear as such by using Protestant language such as “sola scriptura” and “righteousness by faith”, but like with most of their doctrine, they use the same vocabulary as Christian’s but not the same dictionary. This is because the organization seeks to appear like just another denomination, when in actuality, they are not.
The Adventist Church considers themselves to be God’s special, last days Remnant Church, upholding the 10 Commandments with the “Spirit of Prophecy” (the Holy Spirit supposedly speaking in the writings of Ellen G. White) which is supposedly the identifying mark of this being true. They think that the true Church went completely apostate and needed restored so God raised them up as His last day remnant with a “present truth” message for this time.
They believe they have been given a special mission to take to the world—including the Christian world—to leave their churches and come join the “Remnant Church” of they will be given the mark of the beast (which will be worshiping on Sunday when a National Sunday Law is passed) and receive the wrath of God.
Protestantism is more than merely not being Roman Catholic, but means one has roots in the Protestant Reformation. While the Adventist Church likes to try and ride the coattails of the Protestant Reformers, a simple study of classical Protestant theology and history in light of their system tells a much different story.
Their prophetess—Ellen G. White—said that the prayers of those outside of the SDA Church are an abomination to God, that Satan has taken possession of the other churches, that those outside of the SDA Church are faithful servants of Satan, are worse than the heathen, and many other slanderous things.
For more on this watch our extensive break down here.