I had to do a bit of research for this one but here is how I would explain it:
In the 17th century, religion was far more important than it is today. It was a vital part of everyday life. Dutch artists would be influenced by the church of England as their artwork, the Church argued, played a key role in guiding the faithful. Art was certainly as important as the written or spoken word - not locked behind any language barrier - and anyone could understand it. Dutch artists had to make their art persuasive: it had to move the faithful (and disbelievers) to feel the reality of Christ’s sacrifice, the suffering of the martyrs, the visions of the saints.