None whatever. Only when someone adds something to God's requirements for salvation are there obstacles put up. The problem is, creationism is not in God's word, (nor is evolution; the Bible takes no stand on those things) and telling people that one must believe in that modern revision, is causing many to assume Christianity is false.
Usually, even a non-Christian knows something about the earth, the heavens, and the other elements of this world, about the motion and orbit of the stars and even their size and relative positions, about the predictable eclipses of the sun and moon, the cycles of the years and the seasons, about the kinds of animals, shrubs, stones, and so forth, and this knowledge he hold to as being certain from reason and experience. Now, it is a disgraceful and dangerous thing for an infidel to hear a Christian, presumably giving the meaning of Holy Scripture, talking nonsense on these topics; and we should take all means to prevent such an embarrassing situation, in which people show up vast ignorance in a Christian and laugh it to scorn. The shame is not so much that an ignorant individual is derided, but that people outside the household of faith think our sacred writers held such opinions, and, to the great loss of those for whose salvation we toil, the writers of our Scripture are criticized and rejected as unlearned men. If they find a Christian mistaken in a field which they themselves know well and hear him maintaining his foolish opinions about our books, how are they going to believe those books in matters concerning the resurrection of the dead, the hope of eternal life, and the kingdom of heaven, when they think their pages are full of falsehoods and on facts which they themselves have learnt from experience and the light of reason? Reckless and incompetent expounders of Holy Scripture bring untold trouble and sorrow on their wiser brethren when they are caught in one of their mischievous false opinions and are taken to task by those who are not bound by the authority of our sacred books. For then, to defend their utterly foolish and obviously untrue statements, they will try to call upon Holy Scripture for proof and even recite from memory many passages which they think support their position, although they understand neither what they say nor the things about which they make assertion. [1 Timothy 1.7]
St. Augustine De Genesi ad litteram libri duodecim
No matter what the extra requirements are, they are an obstacle to people coming to God. And they are a reason for many to leave the faith.
Glenn Morton is an evangelical Christian, a graduate of the Institute for Creation Research graduate school, and a former YE creationist. Here's his story:
But eventually, by 1994 I was through with young-earth creationISM. Nothing that young-earth creationists had taught me about geology turned out to be true. I took a poll of my ICR graduate friends who have worked in the oil industry. I asked them one question.
"From your oil industry experience, did any fact that you were taught at ICR, which challenged current geological thinking, turn out in the long run to be true? ,"
That is a very simple question. One man, Steve Robertson, who worked for Shell grew real silent on the phone, sighed and softly said 'No!' A very close friend that I had hired at Arco, after hearing the question, exclaimed, "Wait a minute. There has to be one!" But he could not name one. I can not name one. No one else could either. One man I could not reach, to ask that question, had a crisis of faith about two years after coming into the oil industry. I do not know what his spiritual state is now but he was in bad shape the last time I talked to him.
And being through with creationism, I very nearly became through with Christianity. I was on the very verge of becoming an atheist.
http://www.oldearth.org/whyileft.htm
This is the real harm that comes from young Earth creationism.
