As a confirmed secular humanist, having been raised as a Christian and amongst them, neither of these arguments makes any sense to me. Both of them are fallacious, and each constitutes a complete failure to understand humanism. The two assertions are contradictory; but, it doesn't really matter in the end, because neither one is correct, anyway. Consider...
Argument from Egocentrism
Religion and science have historically often clashed (and continue to do so). But, if there is anything secular humanism (conjoined with science) does not do, it is to elevate humanity to some sort of special status in the universe. And, on the other side of the issue, if there is anything religion most often does do, it is to insist upon mankind's special role in, and relation to, 'creation'.
For example, consider the enormous controversy generated by a simple, observationally supported, assertion by Copernicus: the Earth revolves around the Sun (heliocentrism), rather than the other way around (geocentrism). Galileo further upset the prevalent geocentric view---and further bolstered heliocentrism---by, amongst other things, discovering four moons orbiting Jupiter (rather than Earth) and observing the phases of Venus. He was called before the Inquisition for his 'heretical claims', and subsequently imprisoned. His imprisonment was later commuted to house arrest, which remained in place for the rest of his life. (Only a few years earlier, Giordano Bruno was burned at the stake for holding a divergent view from that of the church.)
Why was geocentrism taken so seriously by the church? It was because, in their view, humanity was so vitally all-important to the universe. We exist center stage, placed here by God, for His purposes. To suggest otherwise is to undermine the Almighty Creator and erode our importance to Him.
Of course, by modern standards, the conflict seems ridiculous; nowadays, the Earth obviously orbits the Sun. Yet, an entirely analogous conflict exists today: Darwinian evolution versus creationism. Just as religion was eventually forced to yield to heliocentrism, it continues to be forced to yield to the mass of evidence for evolution.
Heliocentrism is fact.2
Evolution is fact.3
Secular humanism simply puts humanity in its proper place. It neither elevates nor diminishes humans in the universe; it recognizes that humans are just another species, amongst many, in a vast universe in which we play no particularly special part. There's nothing discouraging or demeaning about this any more than saying that the Earth orbits the Sun, rather than the other way around. It doesn't change the fact that we exist, or the capacity for us to do great things or take pleasure in life. It doesn't negate our enjoyment of the company of others or of having children and seeing them flourish, or of being awed by the heavens and the diversity of life here on Earth.
On the other hand, religion is egocentric to the extreme. Amazingly and monumentally so. Honestly, can you think of anything more conceited and self-centered than the following?
The entirety of the universe was made by an omnipotent, omniscient, omnipresent god4 specifically for humanity, and we are the supreme obsession and interest of this god, and are of absolute importance in the grand scheme of things. We are the centerpiece of a great conflict between good and evil, playing out with the Earth at center stage.5 We are so individually important that this god has a plan for each and every one of our lives. In fact, humanity is so overwhelmingly important that our continued existence apparently warrants god-sacrifice!Anyone who believes this kind of nonsense and claims that secular humanism is egocentric has completely failed to comprehend, well, pretty much anything of humanistic relevance. Humanism does not elevate humanity to god status; it simply recognizes that god does not exist6, and we ought to make the best of this very real situation.
If we destroy the Earth through our reckless, shortsighted actions, no one is going to arrive in the nick of time to save us. We'll have no one to blame but ourselves. Humanism charges us with an urgent need to accept responsibility for the consequences of our actions, to strive for our continued survival. Simply put, humanism is realism.
Argument from 'Self' Denigration
It is not uncommon to hear religious people spouting off about how evolution destroys youthful self-esteem by teaching that we're all here purely by accident, and life has no meaning or purpose. Basically, the argument is that secular humanism, along with evolutionary science, devalues life.
Again, I fail to see how this is true. If humanism does anything, it helps us see just how precious life is. Cherish the life you have because it's all you're going to get. It's over when you die. Permanently. Make the most of it; live it, love it, and then make room for others to do the same.
There's nothing shameful about this. There's nothing frightening or dehumanizing about it. It does not reduce the power of our life experiences, our ability to feel pleasure and pain, joy and sorrow. It just emphasizes our accountability for what we do with our time, how we live our lives, what we make of ourselves. The responsibility lies squarely on our own shoulders.
On the other hand, religion is spectacularly destructive of self-esteem. It is the ultimate dis-empowering force, as demonstrated here.
You are plopped involuntarily into the universe, born into sin. Your life is now eternal, and its infinite majority will be spent in either heaven or hell. You're not allowed to permanently die, whether or not you want to 'opt out'.7 So, the choice between heaven and hell is literally the most important one you will ever make. And, the situation is even more urgent because humanity is of critical importance in a great cosmic controversy between good and evil, and you have your own vital role to play. The problem is that you are completely helpless to directly do anything about it because you're intrinsically flawed; you can't get to heaven on your own.8 You are relegated to groveling before god, abjectly begging for forgiveness and mercy so that you might have eternal life in heaven. All you can do is accept your superlative impotence, and hope for the best.9 You live in a constant state of known and admitted total inadequacy.There goes any shred of self-esteem that might have otherwise remained. And, probably the most horrifying twist in this fate is that, somehow, religious people have bought into the idea that this situation is beautiful! Sing with me now, 'Amazing Grace! How sweet the sound that saved a wretch like me...'.
A wretch! And, this is one of the most beloved hymns in existence!
Their life-view is this: live your life independent of god and burn in hell for eternity, or don the shackles of maximum self-abasement and beg god to have mercy on an unworthy worm like you and let you into heaven.
Birthed of religion, the conjoined twin of supreme importance and supreme impotence is a grotesque spectacle indeed. Its effect upon the human psyche is the only excuse I can readily produce to explain the flailing barrage of red herrings, non sequiturs, and other entirely irrational 'arguments' regularly generated by religious people in opposition to secular humanism.
Humanism is about accepting that humanity holds no special cosmic significance, and that this fact simply bears no relevance to our local existence. We still live and breathe, love, learn, and die. And, there's absolutely no reason we shouldn't make a genuine effort to improve life in our tiny corner of the universe in the interim. It's about acknowledging that life is what you make of it, and it's about recognizing that you get out of life what you put in.
Ultimately, humanism is about taking responsibility for yourself, instead of relying upon an ephemeral god-crutch.
So, cherish life. Enjoy it. Dream and work to improve it. It's the most fantastically great 'accidental gift' you will ever receive.
1 To be fair, I must narrow this generalization to Christians in particular. But, I suspect this is primarily simply due to the fact that I was raised amongst Christians. So, keep this in mind while continuing reading.
2 In its original form, heliocentrism was only a little better than geocentrism because it claimed that the Sun was the center of the universe---which, of course, it is no more so than the Earth. However, it was important because it at least correctly recognized that the Earth revolved around the Sun, not vice versa.
3 There are factions fond of bandying the idea that 'evolution is just a theory, not fact'. But, this confuses the scientific meaning of 'theory' with that of the layman. A bumper sticker may most succinctly make the distinction: “Evolution is just a theory. Just like gravity.” (Or electromagnetic theory, or atomic theory, or...)
4 In whose image we are made.
5 This is extremely reminiscent of geocentrism; no wonder it was so important to the old-time theological psyche.
6 In similar fashion, claiming that fairies do not exist does not “elevate humanity to fairy status”; it just means fairies don't exist. And, that's it. Human status remains unchanged.
7 There are variations on this theme, but all of them involve the vast majority of one's life taking place 'after death'.
8 But, you can get to hell on your own; it's the 'default destination'.
9 And all because some idiotic distant ancestor ate a fruit they were told not to touch.