I found the first line in the bible, oddly enough, although the words are changed around slightly: Mt 7:13-ENTER YE IN AT THE STRAIT GATE: FOR WIDE IS THE GATE, AND BROAD IS THE WAY, THAT LEADETH TO DESTRUCTION, AND MANY THERE BE WHICH GO IN THEREAT. http://executableoutlines.com/matt/mt7_13.htm

I was able to find the second part of the phrase on a game info forum:forums.gameinformer.com

Matthew 7:13-14 (New King James Version) The Narrow Way

13 Enter by the narrow gate; for wide is the gate and broad is the way that leads to destruction, and there are many who go in by it. 14 Because narrow is the gate and difficult is the way which leads to life, and there are few who find it.

Luke 13:22-30 (New King James Version) The Narrow Way

22 And He went through the cities and villages, teaching, and journeying toward Jerusalem. 23 Then one said to Him, “Lord, are there few who are saved?” And He said to them, 24 Strive to enter through the narrow gate, for many, I say to you, will seek to enter and will not be able. 25 When once the Master of the house has risen up and shut the door, and you begin to stand outside and knock at the door, saying, ‘Lord, Lord, open for us,’ and He will answer and say to you, ‘I do not know you, where you are from,’ 26 then you will begin to say, ‘We ate and drank in Your presence, and You taught in our streets.’ 27 But He will say, ‘I tell you I do not know you, where you are from. Depart from Me, all you workers of iniquity.’ 28 There will be weeping and gnashing of teeth, when you see Abraham and Isaac and Jacob and all the prophets in the kingdom of God, and yourselves thrust out. 29 They will come from the east and the west, from the north and the south, and sit down in the kingdom of God. 30 And indeed there are last who will be first, and there are first who will be last.”