Don't kid yourself...
Secular Humanists don't believe in the supernatural by definition. Quoting the the Council for Secular Humanism:
Secular humanism is philosophically naturalistic. It holds that nature (the world of everyday physical experience) is all there is, and that reliable knowledge is best obtained when we query nature using the scientific method. Naturalism asserts that supernatural entities like God do not exist, and warns us that knowledge gained without appeal to the natural world and without impartial review by multiple observers is unreliable.
This would certainly rule out belief in Satan, wouldn't you agree?
That's right. Your life is meaningless and totally without purpose, right?
Right.
According to scripture there is only one path to salvation. That is the gift of God; the sacrifice of Jesus Christ on the cross as an atonement for our sin. One needs to receive this gift to be saved. To be sure, many do not believe this at all. No small number think the whole idea is absurd. That is their, and your, God given right. We could talk about such people as Simon Greenleaf, a famous lawyer and a non-believer who set out to prove Christ a fraud. He became a Christian when he studied the evidence. I encourage you to look this up for yourself, but it is not the point of this post.
The scriptural position is clear and so must be the opposite. The goal in keeping anyone from securing salvation is to prevent them from believing on the Lord Jesus Christ as payment for the disobedience that separates all of us from God. It makes absolutely no difference that the person is an atheist, or a Muslim or a secular humanist, or a Satan worshiper. Every one of these “religious” variants gets the job done. Some incredibly popular religions, such as JWs and LDSs have wonderful moral upstanding members. Some even run for president and win super bowls. That doesn’t alter the essential issue; these groups do not hold to the Deity, sufficiency and exclusivity of Jesus being the Christ.
Many have considered that the multitude of religions in the world could not form a better roadblock to Christ. Many Christians have poor scriptural knowledge. Virtually everyone else in the west has only a framework of “children’s stories”; Noah’s ark, Jonah and the whale, etc. This ignorance leaves people in a whirlwind of choices that seem equivalent clouded by lots of unanswered questions. Low-and-behold, there is some form of belief system or form of worship to suit everyone. One thing they have in common, they are all devoid of Jesus Christ. Many people do not bother to choose at all, but that works just fine. Satan’s purpose is accomplished. And while he would prefer to be worshipped, he is satisfied to keep as many people as possible from a relationship with God through Christ.
Obviously this entire structure is built on the specifics of scripture. If one does not believe scripture, or the existence of Christ and Satan then this doesn’t make much sense. I understand that completely. So should you understand the prospective outlined here. It prevents odd claims such as reminders that secular humanists don’t believe in or worship Satan. Of course they don’t; they don’t need to. But from this prospective that doesn’t make secular humanism any less a tool of Satan than Buddhism or Islam.
I say again, disbelieving God is everyone’s God given right. I want to point out that if we Christians are wrong then we go through life (hopefully) behaving morally, sharing our time and resources in order to help others, and encouraging others to do the same. When we die we are gone. BUT if you are wrong you go through life doing what ever. You may be moral or not. You may help others or only help yourself. You may make your neighborhood Christian look like Charlie Manson by comparison. But when you die you will spend an eternity outside of time separated from God. Christ taught the torment of fire. But it seems to me that knowing there is a Being who loves me more than I can comprehend and wants me to be with Him in an amazing place that He created for me, and I refused – that would be hell.