The role of industrialization created several things. From a positive point of view, it produced advancement in terms of technology, but from a negative point of view, it needed man power and resources. And the cheaper the man power and raw materials (or commodities) the better it was for those in power. So, often times, they looked abroad. In terms of religion, missionaries from the west wanted to convert nations and bring Christian values. Some did great work and good things; others were not so beneficial. From the point of the of Africans, some welcomed this new religion, but others were suspicious. Look at Africa today. Some countries are very Christian and proud of it. Finally, in terms of colonialism, European countries were in competition to gain more foreign lands. From the African point of view, colonialism was for the most part seen as oppressive, especially now. One only needs to look at post-colonial literature.
Big question, so I can only give you a little on each thing:
- Industrialization did two things. First, it made it so the European countries needed raw materials. They thought African colonies would be a good place to get them. Second, they wanted new places to sell their goods. If they had colonies, the colonies would have to buy from them.
- Religion -- many people wanted to bring Christianity to the Africans so that became a reason to colonize.
- Nationalism -- the countries were competing to see who was "better" and they all wanted to be seen as the best. So they thought taking colonies was a good way to show their country was best.