In Things Fall Apart, what is Obierika's opinion towards the white missionaries?

In Chinua Achebe's Things Fall Apart, Okonkwo's greatest friend and confidant Obierika is deeply suspicious of the invasive presence of the white missionaries, and is equally concerned by their pervasive influence in the area. Chapter 17 is the key chapter in revealing Obierika's true feelings toward these colonial representatives and the Western norms and values they attempt to impart upon the inhabitants of Umuofia. Obierika sets out to visit Okonkwo, who is two years into his exile in Mbanta, in order to tell him that Okonkwo's son, Nwoye, has joined the ranks of outside missionaries. Obierika is obviously disturbed by Nwoye's decision to engage with the new religion, and this is illustrated by his venture to Mbanta to discuss this matter with Okonkwo. Achebe depicts the settling of missionaries as a disruptive process, and notes that the fact that the incipient church won new converts "was a great source of great sorrow to the leaders of the clan" (142). Obierika is among those who view the influence of white missionaries as problematic and a major source of unwanted change for Umuofia.