Jesus has given us the power to go. He is with us, and if God be with us, who can be against us? There is no way we can fail, not if we are willing and obedient to do it. In Matthew 24 we read:
And this gospel of the kingdom shall be preached in all the world for a witness unto all nations; and then the end shall come.
(Matt. 24:14)
Notice the phrase this gospel of the kingdom. Christians are supposed to know this already, but just for the sake of building a solid foundation, so there can be no doubt about what we are talking about here, let's define the word gospel. Gospel is just another word for Good News. The Gospel of Jesus Christ is good news—not bad news, but good news.

Now it's not good news to tell a sinner that he's going to hell. He probably knows that already. He probably has a good idea now of what is in store for him. It is very likely that he's been told that many times. He doesn't want to be told about hell; he wants to know how to escape it. That's what the Good News is all about. That's what the Gospel is: good news to the sinner about his situation. Don't you imagine most folks are interested in hearing some good news for a change? I think so; in fact, I know so!

Jesus said, "This gospel" (Good News) "of the kingdom shall be preached in all the world for a witness". Now I want you to notice that Jesus said, for a witness. In the Greek text the word translated here as witness literally means "something evidential or with proof or with evidence." This Gospel of the Kingdom shall be preached in all the world for a witness—as something evidential, something with proof or evidence.

Now with that definition in mind, let's read two other Scripture references and see what Jesus is telling us about going and sharing the Gospel with others:
And the gospel (The Good News) must first be published among all nations.
(Mark 13:10)
In other words, "You must go and carry this Good News to the whole world."
And as ye go, preach, saying, The kingdom of heaven is at hand. Heal the sick, cleanse the lepers, raise the dead, cast out devils: freely ye have received, freely give.
(Matt. 10:7,8)
Somewhere down the line we have gotten the idea that witnessing or sharing Jesus meant just getting people saved, but the purpose of being a witness is to bring salvation—full salvation—spiritual, physical, and mental.

Did you ever notice that was how early the disciples did it? They brought spiritual salvation, but they also brought physical salvation and mental salvation. According to Mark 16:20, "They went forth, and preached every where."

They preached the Good News. And what did God do? The Lord working with them, and confirming the word with signs following.

Source: Sharing Jesus Effectively by Jerry Savelle.
Excerpt permission granted by Jerry Savelle Ministries International