Go and Tell.
The striking difference between the Old Testament and the New Testament is the absence of numerous instructions or commandments. In fact, there are just two primary commandments given to Christians.
Love one another
A new commandment I give to you, that you love one another;
as I have loved you, that you also love one another.
By this shall all men know that you are my disciples
if you have love for one another. John 13:34
This command is the basis for all decisions that a follower of Christ makes.
Go and Tell
Jesus came and spoke to them saying,
“All authority has been given to me in heaven and on earth.
Go therefore and make disciples of all the nations,
baptising them in the name of the Father and of the Son and of the Holy Spirit,
teaching them to observe all things that I have commanded you;
and lo, I am with you always, even to the end of the age.”
So, when the chief priests commanded Peter and John not to speak at all nor teach in the Name of Jesus, they replied that they must listen to God rather than man (Acts 4:19).
Therefore it is the primary duty of every Christian to declare what he knows about Jesus Christ, even when governments make it illegal because God’s primary goal is to save as many as will believe in the Lord Jesus Christ.
Arthur Gilmour, 2008