Best known for his poems "Amours" published in 1598, de Sponde was also a great religious poet :
- His Méditations sur quatre Psaumes (Meditations on four Psalms), were dedicated to the king of Navarre in 1588 ;
- Essay de quelques poèmes chrétiens (Attempts to write some Christian poems) including the Douze sonnets de la mort (Twelve sonnets on death), which are a fine example of the baroque style.
In his Avertissement au Roi (Warning to the King), 1589, he tried to convince Henri IV that « il n'est pas bienséant de changer de religion » (changing religion is unbecoming). But in 1593 Jean de Sponde also converted to Catholicism. As a self justification, he published Response d'un catholique apostolique romain au Protestant (Response of an apostolic roman catholic to a Protestant) in 1593, and in 1594 the Déclaration des principaux motifs qui induisent le sieur de Sponde, conseiller et maître des requêtes du roi à s'unir à l'Eglise (Declaration of the main reasons for Mister de Sponde, counsellor and master of claims for the king, to join the Church). Such a reversal triggered off a violent reaction among the Protestants throughout the south-west region and also a general theological debate, especially with Théodore de Bèze.
Agrippa d'Aubigné who had never admitted Henri IV's solemn renunciation also attacked Jean de Sponde « ayant sacrifié son âme pour l'Eglise » (who sacrificed his soul to the Church).
Jean de Sponde, Stanzas for the Holy Supper :
"Ta mort fut notre mort, ta vie est notre vie,
Puisqu'elle est de ta chair et de ton sang nourrie :
Vivant ainsi, Seigneur, craindrons-nous de mourir ? "
(Your death was our death, your life is our life ;
it was your flesh and your blood that nourished it :
living thus, Lord, shall we fear death ?)