"Freedom is not a gift from government. Freedom is a gift from God," Trump said. "That is why we're here tonight, to rededicate ourselves to the defense of our God-given rights."
The main thrust of Trump's speech was tax reform, a key pillar of the Republican agenda the administration says it hopes to accomplish by December.
The President talked up the effort before the conservative audience, saying, "at the heart of our plan is a tax cut for everyday, working Americans."
"We are going to bring back trillions of dollars currently parked overseas," Trump promised, while outlining plans for ending the estate tax and overall simplifying the tax code.
He also plugged a child tax credit for working families being championed by his daughter and top adviser, Ivanka Trump.
He repeatedly praised the organization -- a key mover for Republicans in Washington -- as vital to the tax effort.
"You understand that lower taxes mean bigger paychecks, more jobs and stronger growth," he said.
He called on the audience to help push the plan, which is still in the works, through Congress.
"We need the help of The Heritage Foundation and everyone here tonight to get our tax cuts through the House, through the Senate and to my desk for signature," Trump said.
Trump anticipated he would need the full support of Republicans in Congress to pass the bill and blasted Democrats as "obstructionists." But he said that, if successful, they would have "the largest tax cut in the history of our country."
Earlier in his remarks, Trump touched on a few cultural issues, including "respect" for the US flag.
"We believe that our great American flag should be treated with reverence and respect," he said, adding that young Americans should be taught to respect it.
And he began his remarks lamenting people calling for the removal of Christopher Columbus statues.
"We believe we should preserve our history, not tear it down. Now they're even trying to destroy statues of Christopher Columbus, what's next? It has to be stopped. It's heritage," he said.
He closed his speech with an oft-repeated pledge to bring back "Merry Christmas," tying the holiday to the stated desire for movement on the tax plan in December.
"Let's give our country the best Christmas of all: massive tax relief," Trump said.