The symbolic meanings of the cross

In the beginning of the story the symbolic meaning of the cross is quiet unclear. The Director put it up to mark the grave of the former and first chief of the station who died of fever, but if he really died because of this is a little bit uncertain.
The cross is a Christian symbol first and foremost, Jesus died at the cross for our sins. But in the wilderness of the Congo it seems a little lonely: Kayerts and Carlier don't really believe in the Christian religion, Makola believes in the evil spirits just like the other "savages", who lived around the station - therefore no one appearing in the story actually believes in the Christian religion and so the cross is reduced to its cultural value, representing a religion that is more a cultural aspect than a vivid devotion. The cross is also a symbol for colonialism. When the first Spanish seamen came to America, they forced the natives to convert. One of the reasons, why the Spanish royal house sent missionaries to explore the entire world is to spread Christianity. If the natives refused to convert they were killed. The crusades followed a similar pattern. Since such times of violently expanding the Christian fellowship the cross also became a symbol for oppression, force and repression on the one hand - but as far as the missionaries themselves are concerned also for progress, sense of mission and development.
But in the wilderness of the Congo the cross is as useless as its symbolic meanings. It is as useless as Kayerts and Carlier and the station. When the strangers come and see the cross, they are irritated by it, they don't understand the meaning or the use of it. This may be a hint of its senselessness.
When Carlier and Kayerts first see the cross, they both get the same image on their mind: What happened to them if one of them would die? (p. 13, l. 48-49, 57-58) This foreshadows the later course of the story and returns when Carlier replants the cross which is ironic when you think that Kayerts later commits suicide there. Both Carlier and the Director pave the way for Kayerts tragic death.
After Kayerts shot Carlier he feels despaired and lost. He sees the cross in the fog and it seems to him as the only place he can turn to. If he already has the intention to kill himself is not shown clearly. Maybe, in the last moments of his life full of despair, he has nobody to beg to but God. But even there he gets no help, the station is dropped by the natives, the Director and even by God. The only solution is to follow the former chief and die under this useless, forelorn cross.
Ultimately the cross may be seen - concerning the whole background of the story - as a symbol of the colonizer's futile mission.