Much of this has been historical – providing substantial and novel reassessments of British idealists such as Bernard Bosanquet but also of Maritain (who, Sweet argues, converge on a number of significant points).

Sweet's contributions to the philosophy of religion and philosophical theology are developed over two single authored, one co-authored, and several edited books.

Sweet travels extensively, and regularly lectures or teaches in East Asia, India, and Western Europe.

He has been a major contributor to the international programmes of the Council for Research in Values and Philosophy and of the World Union of Catholic Philosophical Associations and the Istituto Internazionale Jacques Maritain (of which he is Presidente d'onore).

His work has been published in Castilian, Chinese, English, French, Gallego, German, Italian, Persian, Polish, and Vietnamese.