Pieter studied architecture, served from 1968 till 1982 as cityplanning consultant in Holland and abroad. In these years he developed a philosophy of planning on a biblical basis and taught on this and related topics at conferences and universities. 

Helene studied psychology and worked as selection-officer. She developed a biblical understanding of sexuality and marriage and taught extensively on this and related topics in churches and conferences, and pioneered (prophetic) counseling in Holland.

Both Pieter and Helene are students of Dr. Francis Schaeffer. In the seventies they established and led a Christian residential community. 

In 1983 God called them to full time missionary service with Youth With A Mission, Amsterdam. In 1986 Pieter pioneered the Amsterdam City Prayer; in 1987 he pioneered the City Prayer Movement in Holland, which he coordinates since then. In 1988 he felt led to call a, first ever, European prayer leaders conference. In 1992 he co-founded, and since then co-led, the European Prayer Link (EPL). He was the Central European Coordinator of the Spiritual Warfare Network (SWN) of the former AD 2000 Movement. Both in his professional period and as a missionary he has published articles; he is in the proces of publishing a trilogy "The City Redeemed."

Pieter and Helene travel extensively, together and individually, in Europe and beyond, to teach and to lead intercessory actions, to small audiences and in relation to UN-conferences. As their involvement developed they felt led, in 1998, to establish a separate foundation for their ministry, "Serving the Nations." Their burden, to contribute to the preparation of the Church and the Nations for the end time, increased as they travelled.

Calling

Pieter: My calling is to give intercessors and spiritual and government leaders biblical hope and help that their peoples, nations and cities can be redeemed. 
"On this mountain the LORD Almighty will prepare a feast of rich food for all peoples... he will destroy the shroud that enfolds all peoples, the sheet that covers all nations" (Isa 25:6-7)

Helene: My calling is to discern spiritual dynamics in societal developments from an end time perspective, and to help spiritual and political leaders to understand the times. 
"... to turn the hearts of... the disobedient to the wisdom of the righteous--to make ready a people prepared for the Lord" (Luke 1:17b)

Pieter and Helene (born both in 1940) have four children.