Lubbertus did not come to the aid of Calvin's successor, feeling that as Saravia was in the Anglican Church that his views would not have the power of appeal in the Netherlands that Beza feared.
[3] In 1601 Lubbertus wrote against Robert Bellarmine in De conciliis libri quinque, Scholastice & Theologice collati cum disputationibus Roberti Bellarmini.
Lubbertus is best known for his opposition to the position of Hugo Grotius, who defended the right of the civil authority to place whomever they wished into university faculty.
Lubbertus rose to the attention of the Dutch civil authorities who had sided with the Remonstrants with his publishing of a 900-page book Commentarii ad nonaginta errores Conradi Vorstii which opened with a dedicatory letter to George Abbot, the Archbishop of Canterbury.
In the dedication he attacked the States of Holland and other authorities for appointing Vorstius to professor of Divinity at Leiden University and accused them of introducing Socianianism into the Dutch Church.
[5] In response to Lubbertus' work against Vorstius, Hugo Grotius (a representative for Rotterdam and the acting Judge Advocate of Holland) wrote Ordinum Pietas in 1613.
This caustic polemic not only attacked Lubbertus' views but called him out in print (such as listing a number of quotations of Church Fathers and then saying "What are you going to reply to this mass of examples - Sibrandus?"[6]).
[7] In February 1614, Lubbertus, calling Ordinum pietas by Grotius "arrogantia", attacked its reasoning in Responsio Ad Pietatem Hugonis Grotii.
"[6] Lubbertus accused Vorstius of using deceit to attain a position with the appearance of orthodoxy in order to covertly slip heretical works and ideas into his lesson plans.
[6] Lubbertus did not use as many sources as his opponent in his response to Grotius, basing his arguments "mainly on a collection of the acts of councils and a number of quotations of Augustine, and using Stephanus' Thesaurus for broader ancient material".