I can think of many reasons why an elector would not cast a vote for Trump, but this person's reasoning, while heartfelt, is also plainly unconstitutional.
"I do not see how Donald Trump is biblically qualified to serve in the office of the presidency," he said in his Saturday post. "Of the hundreds of angry messages that I have received, not one has made a convincing case from Scripture otherwise. If Trump is not qualified and my role, both morally and historically, as an elected official is to vote my conscience, then I cannot and will not vote for Donald Trump for president."
Article VI, clause 3 of the Constitution plainly states "no religious test shall ever be required as a qualification to any office or public trust under the United States."
By bringing biblical qualifications into his reasoning, Art Sisneros is clearly applying a religious test. While he states he will resign rather than cast a vote for Trump, I wonder how long has he been an elector, and how many times he's applied a religious test for office in violation of the Constitution?