President Joe Biden decimated Donald Trump, his promises of authoritarianism and his attacks on American democracy in what is being called one of his “most powerful” speeches ever, from a stage just miles from historic Valley Forge, Pennsylvania. “This may be the most powerful speech — just a few minutes in — Biden has ever given,” wrote The Messenger’s politics editor Marty Kady. “He’s going at Trump by name and head on and I love it. And the country needs it,” observed former Republican U.S. Congressman Joe Walsh. “Republicans cannot defend what Joe Biden is forcefully calling out. They just…