I just don't understand this

So John Piper has harsh words regarding President-elect Obama's decision to invite Gene Robinson to pray at the inauguration.

I just can't figure out why Piper, whom I generally respect, has decided to join the rank-in-file of American evangelicalism's obsession with homosexuality. I'm wondering, based on Piper's logic, if Christ becomes a minister of condemnation every time an obese pastor steps up to the pulpit? what does the lying deacon make him? or the elder who cheats on his taxes? What's more disturbing is the implicit assumption that the American president should endorse a view commensurate with Piper's evangelical belief system. This is the false assumption that is killing the evangelical church in this country. Instead of preaching a robust gospel that attracts the public, we push our views into the mainstream by crying foul every time we think someone has stepped on our toes. Believe it or not, there are other citizens in this country who embrace views very different than our own. Believe it or not, the best way to reach them is by drawing them in, not selfishly pushing our way on them (especially in the political arena).