Non-Christian = Atheist, not Satanist!
I believe this fellow was speaking exclusively in very loose, and general terms, since Christianity's interpretation of Satan, and Christianity is at this moment, and time...the religion opposing the satanic faiths in question.
Hinduism, Buddhism, and the other Eastern faiths do not have a satanic figure if I recall correctly, being based entirely at its root on the cyclical phases of nature, applying material, and natural physics to a spiritual concept.
Islam, and Judaism have satanic figures:
Satan in Islam is named Iblis, of which I am not familiar with Islam's view on Angels, or Heavenly originated beings.
Satan in Judaism being the Accuser, the one who goes before God and says:
"Behold this man, if you were not so kind to him, he would surely become depraved and truly evil."
Satan according to Christian belief, which in addition to his role as an Accuser of man, he is also a tempter of spirits, and a corrupter, a being (fallen angel, of which many traditions say he was a Cherub [a warrior angel]) who fell from his high place and accuses mankind, a malevolent force that gave birth to, and represents, all that has been perverted, or tainted, from its original neutral, perfectly devised, and 'good' state.
He is not all powerful, and is not a god. He is a fallen servant, a being that is the avatar and source of evil, since in the primal beginnings, it was he who first became evil.
Evil coming from within himself: His pride, which lead to greed, which lead to rebellion against God, and in that rebellion he perverted God's creations to his own ends, and sought to take the throne of God, to be a god above God, with mankind to worship him instead (since he believes himself to be higher than God).
And having tainted mankind, and caused them to sin, perverting them, and assuring that no man born afterwards could be sinless, in essence, 'owned' mankind. And mankind now bound to sin, became embroiled in a war with God, becoming pawns for the malevolent force that Satan had become.
In their constant sinful natures, they sentenced themselves to death. Crimes against God and humanity committed on a daily basis, and even the 'littlest' sins have a resounding impact in the strands of time.
A white lie seems like a tiny drop, until it ripples so far outward, those ripples moving little leaves, and causing problems that echo into eternity...take into account the hundreds of white lies we tell every day...That gets the point across...
And so in order to pardon mankind of their sins and clean them, they had to be bought back, and since the price for a life is another life, and billions of lives in a state of being for sale, it required a sacrifice of equal measure to the multitude.
An angel's life would not suffice, an angel is a servant. The life of a man who has sinned is already owned, tainted, and cannot buy the lives of his fellow slaves. But the life of a God met the bill, and that is where Christ makes his debut.
Satanism: at its loosest, and most basic definition is the act of rejecting the side of God in favour of those who war against him. IE: choosing the side that wants to strike at God, or pervert his creations, or to harm his servants/children.
More specifically, Satanism is the worship, reverence, or adoration of Satan as a concept, literal being, or as an ideal.
Satanic: anything relating to Satan, demonic entities in Abrahamic theology, or perhaps, something similar to those concepts.
(Slaneesh, Khorne, and Horus, from Warhammer could be considered "satantic" images, or ideas)
On the issue of Atheism, and Satanism.
Atheists, and Agnostics are neutral countries in a war of empires. Not to say they are not effected, or that they are safe...but they are not combatants in a Satanic, or Godly fashion. Unless perhaps they are being guided towards some end unknowingly, by one side or the other. Either guided for the greater good, or for the greater perversion. This however, does not exclude Atheism, or Agnosticism from becoming third party war-bearers and attacking either side.
As for my personal thoughts...
I don't know why anyone would seek to worship a malevolent being, much less a servant who became malevolent, for the mere sake of being rebellious for rebellion's sake, a servant who is not all powerful by any means, the weaker combatant in every sense of the word.
Purposeful rebellion against "restrictions" put in place for the good of humanity, and for the reasons of health, restrictions that are just, is not conducive to building a legacy, or maintaining your bloodline or the health of it. Neither is it good for a benevolent and worthwhile social status, or for the honour of your family and person. And this isn't even taking into account the Spiritual aspects of such a choice.
Being rebellious, and going into a room and touching a highly dangerous electrical current, just because a sign says 'don't enter, and don't touch' and doing so simply because you don't want to 'be told what to do' or be 'restricted', is a dumb idea.
You can't have kids, raise them, pass on your legacy, if you are dead...
You also can't enjoy life to its fullest, if you are dead. Sure you felt really alive for that brief moment you were being shocked and burned alive inside...but you didn't feel alive for long...and probably felt absolutely nothing shortly after....being dead...
As for the spiritual aspect...that's rather obvious...