His work spans religious subjects like Christ Crowned with Thorns and mythological scenes such as Paris and Oenone. Lois often used a restrained colour palette and focused on the physical presence of his subjects. The X-radiographs of his portraits reveal the hidden layers of his process, showing how he adjusted the placement of features or clothing. These technical studies provide a look at the artist's decision-making and his search for formal balance.

Modern collectors value the quiet authority and historical weight of these Dutch Golden Age works. The portraits offer a window into the social hierarchy of the Dutch Republic through precise details of dress and posture. His religious and mythological scenes provide a sense of drama without being overly decorative. These prints work well in contemporary interiors that favour clean lines and classical subjects with a sense of history.