He was the executive director and then president of the Center for Public Justice (a Christian policy thinktank) from 1981 to 2009, when he retired from the organization.
Today, Skillen speaks regularly both domestically and internationally and writes primarily in areas of biblical studies and political philosophy and practice.
Skillen studied philosophy at the Free University of Amsterdam in 1969–70, focusing particularly on the work of Herman Dooyeweerd, Professor of Law and renowned Christian philosopher.
His works include The Scattered Voice: Christians at Odds in the Public Square (Zondervan, 1990), which was described as "remarkable" and "meticulously fair" by Prof. Mark Noll, then at Wheaton College.
In 2009, he signed a public statement encouraging all Christians to "read, wrestle with, and respond to Caritas in Veritate" the social encyclical by Pope Benedict XVI.