What were the two goals of the Declaration of Independence?

The first goal of the Declaration of Independence was to outline the legitimate complaints of the colonists against Parliament. Keep in mind that many in the colonies still saw a compromise as possible between the colonies and Britain. Several people were worried that independence would lead to unintended consequences such as a domestic tyranny or foreign takeover. Jefferson outlined the abuses against Parliament and even stated that the people had a right to abolish the government when it did not protect life, liberty and the pursuit of happiness. Jefferson even states that the decision to overthrow the government should not be taken lightly. By doing this he makes the colonists appear quite reasonable. Jefferson hoped that this document might push some colonists into supporting the independence movement.
The second goal was to state what the ideals of the new government would be if and when the colonists succeeded in gaining their independence. It is easy to forget that the colonists did not know how the revolution would end. Jefferson stated the lofty goals that government existed by consent of the governed and that the people should have the rights of life, liberty, and the pursuit of happiness. This was an ideal government, as in the colonies at the time everyone did not enjoy these rights as slavery still existed.

The main goal of the Declaration of Independence was to persuade reluctant colonists that there was no longer any hope of compromise with Britain and that it was therefore necessary for America to proclaim its independence. It may seem strange to us in the present day, but a large number of colonists genuinely believed that some kind of amicable settlement with the British could still be reached. The declaration, with its extensive list of grievances against King George III, aimed to disabuse them of their increasingly unrealistic hopes.
An additional goal was the establishment of the primary function of government as the securing of inalienable rights such as "life, liberty, and the pursuit of happiness." Many Americans felt that their ancient liberties under the unwritten British constitution had been systematically violated. It was therefore important that the principles on which government should be based were clearly articulated and written down for all to see.