Again, the teaching of creationism in public school science classes is not allowed for two simple and obvious reasons: it is unconstitutional and unsubstantiated religious beliefs aren’t science. So why do you think Christians keep trying to impose these beliefs on others?
#1. They are not "unsubstantiated religious beliefs," God's creative accomplishments predating religion by eons and the work of His hands being evident to religious and non-religious alike:
"What may be known about God is plain to all, because God has made it plain to them. For since the creation of the world God's invisible qualities--His eternal power and divine nature--have been clearly seen, being understood from what has been made, so that men are without excuse."(Romans 1:19-20) The difference being, of course, that believers admit, accept, and revere the Truth which non-believers vainly attempt to ignore, deny, or cover it up so as to be able to continue to worship themselves.
#2. There are--for the moment, at least--more children of Christians in the public schools than children of atheists (who their parents feel need to be shielded and protected from exposure to the Truth at all costs), and also most thoughtful persons would hold that evolution--at least in the hard-core darwinian sense--is an the epitome of an "unsubstantiated religious belief", it seems only fair to provide equal time for both viewpoints to be taught, even at the risk of exposing atheist children to the Truth.
Atheism, of course, is every bit as much a religion as Christianity, even if it is the worship of nothing, and should have no more power to dictate public policy than atheists accuse Christians of trying to do.
However, religious believers have enacted blasphemy laws with these penalties in many countries around the world. It is a fact. So why do you think religious believers enact blasphemy laws with penalties so out of proportion to the offence? What is it in the psyche of religious believers that causes them to tend to such unjustified extremes?
i have given your question a lot of thought over the years, and have come to the conclusion that the extreme measures that supposed "believers" take in supposed "defense" of their beliefs and their deity seems to stem from a lack of experiental knowledge of that which they are "defending". Thus, there are "believers" whose beliefs are all in their heads and Believers whose beliefs reside in their hearts--along with that which they worship.
Once a Truth has been personally experienced, there is no longer a need to defend it beyond explanation and, in a dire situation, debate. It MUST be shared but MUST NOT be used as a club to beat down the opposition--let alone as an excuse to destroy them. The closer to God one gets and the more experientally vital the relationship with God becomes, the more loving, forgiving, and tolerant of the beliefs of others one becomes.
For example, there are Moslems killing indiscriminatly in a most brutal and unconscionable manner in the name of Allah, attempting to earn a place in "heaven" by their barbarisms; and there are, likewise, also Moslems such as the Sufis who are loving and peaceful, and write some of the most beautiful poetry about their "Beloved" that the world has ever seen.
Likewise, in Christianity, there were those who perpetrated the horrors of the Inquisition--demented and hate-filled opposites to the Lord they claimed to be serving and the Gospel of Peace which they claimed to be defending--and, diametrical opposites, those, like the Quakers, who demonstrated so well our Lord's Commandment to "love your neighbor as yourself."
The difference is in the personal experience--or lack thereof--of the person in question. Those with personal experience of God become God-like, those with only doctrine to hang on to become God's anthesis. If one is comfortable and confident regarding their beliefs they will be tolerant of those held by others--even if they hold them to be misguided, wrong, or even threatening (knowing, of course, that Truth always triumphs in the end). If one is not confident and comfortable with a belief system they hold, they will do everything in their power to discredit and/or destroy opposition which they feel threatens what they "believe" but have never experienced the truth of for themselves.
A perfect case in point regarding the latter would be the atheistic attempt to destroy Christianity--and all religion--in the countries they managed to take control of in the middle of the last century such as the Soviet Union, Communist China, North Vietnam, North Korea, etc. where millions upon millions of religious believers were slaughtered by atheist governments trying to stamp out the Truth in support of a god-less philosophy which was doomed to failure from the start
--specifically due to its godlessness and atheistic insistance that human beings are just evolved animals rather than creations of a Loving God who made them in His Image and Likeness.
Vincent Carroll and David Shiflett write, "If ideas matter, then a religion that intones 'blessed are the peacemakers' has more likelihood of restraining human aggression than a philosophy which demands that all oppositional ideas and those holding them be destroyed in gas chambers, labor camps,or in psychiatric "hospitals" where they can be chemically tortured into accepting the assertion that "god is dead". And a religion whose central rite included prayers for peace even during the Crusades has a better chance of fostering subcultures of antiwar dissent than religions that lack such ambiguity. The New Testament Gospel--and all those who take it literally--are dead set against killing, and stubborn literalists in every era have taken its message to heart. Their failure to create peace on earth is not nearly so surprising as the fact that against such overpowering odds, they tried."
So you might think about changing your question to "Why do atheists act with such unbelievable hatred and brutality towards believers in a God Who is Love?" If you are honest, the answer might save the soul you deny you have.
A BOND-SLAVE/FRIEND/BROTHER OF OUR LORD/GOD/SAVIOR JESUS CHRIST,
ephraim