I was going to suggest the same thing that Pilgrim did. In other words, use the arguements that they use on the site that Wes has suggested, but unmask those arguements by stating their position clearly without the use of euphamisms and hiding the self serving purpose of it all.
As to the outcome, your grade and credit, that you would have to leave up to the Lord, trusting Him to either give you favor in their eyes, or to uphold you if this is taken badly and enrages them. I have found that the Lord does both, depending on His will. Sometimes it has cost me dearly in physical terms to take a stand for Him, but there has always been a spiritual blessing, if nothing else the peace of conscience that only He can provide.
