The Kongo church was always short of ordained clergy, and made up for it by the employment of a strong laity. Kongolese school teachers or "mestres" were the anchor of this system. Recruited from the nobility and trained in the kingdom's schools, they provided religious instruction and services to others building upon Kongo's growing Christian population. At the same time, they permitted the growth of syncretic forms of Christianity which incorporated older religious ideas with Christian ones. Examples of this are the introduction of KiKongo words to translate Christian concepts. The KiKongo words "ukisi" (an abstract word meaning charm, but used to mean "holy") and "nkanda" (meaning book) were merged so that the Christian Bible became known as the "nkanda ukisi". The church became known as the "nzo a ukisi". While some European clergy often denounced these mixed traditions, they were never able to root them out.