In 1777, he drafted An Act for Establishing Religious Freedom. (1) In 1779, he became Governor and introduced the act into the legislature. However, strong opposition from the primarily Anglican "old guard" stalled the bill. An alternate bill was advanced by Patrick Henry. It proposed that Christianity become the established religion of the State and that all denominations be given equal privileges.
Jefferson's bill gradually collected support from Baptists, Presbyterians, freethinkers, Jews, a few Anglicans, people who were tired of religious conflict and others. A dramatic speech by James Madison (1751-1836) to the Virginia General Assembly called A Memorial and Remonstrance (2) dramatically swayed support for Jefferson's bill. Somewhat amended, (3) it became law on 1786-JAN-16.
The key part of the act, Section II reads:
"II. Be it enacted by the General Assembly, That no man shall be compelled to frequent or support any religious worship, place or ministry whatsoever, nor shall be enforced, restrained, molested or burdened in his body or goods, nor shall otherwise suffer on account of his religious opinions or belief; but that all men shall be free to profess, and by argument to maintain, their opinion in matters of religion, and that the same shall in no wise diminish, enlarge, or affect their civil capacities.'