God has always had the purpose of making Himself famous throughout the whole world (also see Galatians 3:7-9), not because He is egotistical, but because He wants the entire world to know Him and be transformed by His love. How can we possibly keep our faith to ourselves?
41 “Likewise, when a foreigner, who is not of your people Israel, comes from a far country for your name's sake 42 (for they shall hear of your great name and your mighty hand, and of your outstretched arm), when he comes and prays toward this house, 43 hear in heaven your dwelling place and do according to all for which the foreigner calls to you, in order that all the peoples of the earth may know your name and fear you, as do your people Israel, and that they may know that this house that I have built is called by your name.— 1 Kings 8:41-43, ESV
William Carey is known by many as the "father of modern missions." Image from Wikimedia Commons