Churches and other religious organizations are considered to be charities by the Internal Revenue Service (IRS). That means they are tax exempt. But that tax exempt status has a requirement to be maintained -- the religious organizations cannot involve themselves in partisan politics. They can encourage political participation of their members, and they can encourage members to vote. But they cannot instruct their members to vote for a particular party or a particular candidate.
Donald Trump wants to change that. He knows that he got significant support from right-wing fundamentalist church members in the last election, and he knows that those members (and their church leaders) tend to support his Republican Party. He now wants to reward those churches and church leaders for their support, and insure that they can campaign for him and his party openly in the future. Toward that end, Trump says he wants to change the rules to allow churches to participate in partisan politics while keeping their tax exempt status.
This is just wrong. It is a huge benefit for churches and religious organization to not have to pay taxes. And the taxes they don't pay has to be made up by all individual taxpayers (even those who are not members of that organization, or any religious institution). It is bad enough that they don't have to pay taxes, but it is ridiculous to allow them to participate in partisan politics while paying no taxes.
It is also against the will of the American people. Poll after poll has shown that a significant majority of Americans don't want partisan politics preached from the pulpit. They like the rules as they are. But on this issue, just like many others, Trump doesn't seem to care what Americans want. He is going to act for the benefit of himself and his party, regardless of what the public wants.
This change to the IRS laws must be opposed.