From The Life and Times of Bruce Gerencser:
Many people were upset over Trump signing his name on Bibles. “Is he the author of the Bible?” one man rhetorically asked. Of course not, but neither are the men this man thinks ARE the authors. Most of the books of the Bible are written by unknown authors. Of course, this fact is not preached from Evangelical pulpits. Preachers mustn’t ever say or do anything that would cause parishioners to doubt that the Bible is the inspired, inerrant, infallible Word of God.
Those upset over Trump “defacing” the Word of God are ignorant of Evangelical Baptist church culture. It is not uncommon for Bible owners to write inside their Bibles: the date/time/place they were saved, the date/place they were baptized, and their life verse.