Separation of church and state is easy to understand. All you need to do is too look at Church and State as two teams competing in sports. The State has all the money and all the power. The State has armies and it can make laws, that it can enforce using police and jails. The Church can collect money and make its own rules but it cannot enforce these using armies, police and jails. It has to use an honor system without legal binding contracts. The Church has much weaker hand and is playing the game at a severe disadvantage, relative to the State.
Separation is not about giving the powerful and rich State even more power and money. It is about limiting the power of government, when it play with the Churches, so it is a fair competition. The Church cannot have an army or make laws so it can compete at the level of the State. The other way is the only logical option; make the State play by the rules it gives the churches. For example, tax exemptions for churches is one way to limit the power of the government; IRS cannot be used as weapon, since the Church can't do this back to the State.
The State also needs to be restricted in terms of making laws against Churches since only it has police and jails. The Church cannot do this back to the State. How about having the Churches make laws against lying politicians that can be enforced with jail? A church can grow, but it can't do this with force, with armies or with laws, as can the State. It has to appeal to people in a civilized way without using power, money or force. These rules should also apply to the State when dealing with the Church to make it fair.
The Democrats believe in big Government that interferes in all aspects of life. The Church is off limits, due to the State not being allowed to cheat. However, since the Democrats want to expand big Government, they will cheat and use even dual dress standards, to get extra power from the Churches.
The real problem is many of the people who have power in the State understand they do not need talent to make people do things. Power can be used to implement and force moron things. If you have no power, like the Church, relative to the State, you need extra talents since you can't force anything. The Democrats think they need to cheat to win, since they have so many hacks in positions of power. They cannot play by the harder rules of the Church and win; public appeal without force. When Trump removes regulations is moving the bar to where the Churches are, which is limited control over people using force. This is why the religious like him.