Who shall tell them?

The word evangelism comes from the Koine Greek word εὐαγγέλιον (transliterated as "evangelion"). The Greek word εὐαγγέλιον originally meant a reward for good news given to the messenger (εὔ = "good", ἀγγέλλω = "I bring a message"; the word angel is of the same root) and later "good news". The term evangelical, which is widely used today also stems from this word. On the other hand, our modern word "Gospel" comes from the Old English word "Godspell". In Old English, "god" with a long "o" meant "good", and "spell" meant "word" (we carry this meaning also in our word "spelling"). So in other words, "Godspell" meant "good word", specifically the good tidings concerning Jesus Christ.

Understanding the etymology of the word Gospel and Evangelism shapes the way I understand how evangelism ought to be done. Evangelism involves proclaiming the good news concerning the atonement of sins made by Jesus Christ on the cross. The power of that Gospel message we believe in should be so compelling that we would want to share it with everyone and anyone - from your family members to the stranger on the street, since it is the power of God to salvation for everyone who believes, for the Jew first and also for the Greek (Rom 1:16). True, one's lifestyle does have to support the good news you carry, but living a righteous life while waiting for people to ask why you live as such does not constitute as evangelism.

So one may share the Gospel with a stranger on a bus and never see that person again, or one may share the Gospel with a close friend and continue to follow up on them so that they can witness the reality of the Gospel; Either way, it makes no difference - the seed of the Gospel has been planted, being used by the Holy Spirit to convict them; so long the Gospel is proclaimed.