I was one time, not long ago, challenged indirectly (as the challenge was actually meant for evangelical preachers) by a pastor, who is not evangelical, that where in the Bible does it say that we are to go out and preach. I thought to myself, is she kidding? or perhaps she was talking about preaching to strangers on the streets? which shouldn't really make a difference because the Bible says preach to the whole world, not just people we know or people we like or people who like us. Or was it that those commands by our Lord are applicable only to some Christians but not all? which is absurd for all christians are disciples of the Lord.
I did not reply because I believe it sounded like a rebellious question. Though I believe I should have responded. So I was wrong.
As to the answer, it is simply, which no Christians should not know, but I thought I would expand it here, so that there is no excuse:
Matthew 28:18-20 (...teach/make disciples of all nations...)
Mark 16:15
Acts 10:42
James 2:14 (Indirectly...but a command is a command nonetheless)
John 14:15