He is a violent criminal and a terrorist that was very likely motivated by racial hatred. And he is a prime example of a dangerous and growing problem in the United States -- domestic terrorism.
Recently, the Trump administration disbanded an investigative group within the Department of Homeland Security -- a group that focused on domestic terrorism (including that done by white supremacists and nationalists). This was not surprising, since Trump has refused to condemn (or separate himself) the white supremacists and white nationalists -- calling them "good people".
This was just the opposite of what should have been done. White domestic terrorists pose a far greater threat to this country and its citizens than any foreign terrorists -- and that threat is growing. Our government needs to focus more on these domestic hate terrorists -- not less.
Matthews faces a possible 15 year prison sentence. If convicted, he will deserve every day of that sentence.
NOTE -- Regular readers of this blog will know that I am an atheist. But I am also a strong believer in the U.S. Constitution that guarantees freedom of religion. That gives every American the right to believe in and practice the religion of his/her choice (or not believe in any religion). Criminal acts against religious people for their beliefs is wrong -- just as wrong as trying to force your religious beliefs on others, or using your religion to discriminate against others.