"Go ye therefore, and teach all nations, baptising them in the name of the Father, and of the Son, and of the Holy Spirit: Teaching them to observe all things whatsoever I have commanded you: and, lo, I am with you always, even unto the end of the world."
These final verses of the Gospel of Matthew are often called the Great Commission. They are deemed by many Christians to oblige them to spread their faith to everyone, under the assumption that God requires everyone in the world to become a Christian.
The Qu'ran lays a similar obligation upon Muslims:
"Invite (others) to the way of your Lord with wisdom and beautiful preaching, and reason with them in ways that are best."
On the other hand, Hinduism, Buddhism, Judaism, Sikhism and most other faiths do not have this obligation to seek converts. Some actually refuse to accept converts. ISKCON, the International Society for Krishna Consciousness is a Hindu exception.
Colonialisation is the inevitable outcome when a technologically-advanced culture encounters a less advanced one. it can be military, commercial, religious, social and sometimes voluntary. It can even happen unintentionally as a result of local politics or self-defence. History is a messy business and no two cases are alike.
When the Roman Catholic Church followed the Normans into Britain, everyone ended up a Catholic in so far as going to church, etc. But most rural British people maintained their pagan beliefs until the 19th Century at least. They are the basis of many of our 'quaint and charming' traditions, including Easter eggs and the Easter Bunny, the Christmas Tree, gifts, lights and Father Christmas (Santa), well-dressing, Morris Dancing, maypoles and so on. At heart, and even if they won't admit it, most British people are still pagans. It seems that the British missionaries did a better job in Nigeria than their ancestors managed in Britain!
As to the "My God's better than your God" thing, it does seem to depend on the religion. As two of the younger religions, I suppose it makes sense for Christianity and Islam to be the most aggressive recruiters!
