One of the outward expressions of worship is evangelism. We can express God’s glory back to Him (upward worship), to ourselves (inward worship), and to the world (evangelism).
Not only are we commanded by the great commission to go forth into all the world and preach the gospel, but the very essence of the message demands that it be told. If, as in fact, every man on earth should die in a state of horrific sinfulness, alienated from God and under His Wrath, but the all-powerful God of all the universe–even while these men were still His enemies–made a propitiation for the sins of an elect, and ransomed them from their condition of filth, not only imputing His own righteousness to us but guaranteeing by Himself that He would sanctify us and glorify us as to be perfect, righteous and worthy to spend eternity with Him. When that story includes One of the glorious Persons of the Trinity becoming a little child, teaching with infinite wisdom, focused on one purpose, and dying as a passover lamb to redeem the elect; When God His Father raises the King of life back to life, conquering sin, death, and the curse. When the story has been revealed to you by the Hand of God Himself (through the Apostles and Prophets), are you going to timidly sit back and keep it a secret? Not a chance. The gospel is a story that needs to be told. How badly do you have to hate someone to not proselytize?
As an outward expression of worship, evangelism is core to the mission of glorifying God. In addition, it is the chief means of expanding Christ’s kingdom, and bringing all men under the dominion of Christ.
Don’t be timid.