Sharing the gospel isn't an elective--it's required, important, and expected. Since "faith comes from hearing, and hearing through the word of Christ." (Romans 10:17) believers must be obedient to proclaim Christ to the world.
Many Christians, for whatever reason, disobey God's call to "go into all the world and preach the good news to all creation." (Mark 16:15) Why? Fear of rejection? Lack of knowledge? Being pushed outside of comfort zones? We shouldn't fear! Once we are obedient, the Holy Spirit can speak through us to change hearts--even our messed up words. He can use anyone--even you and me. We are all sinners and can't be perfect witnesses, but He can and does use us to spread the Message of Christ. True, we need to continue to study the Word to grow in our knowledge and understanding so we are equipped and can confidently share with others. If sharing is outside of your comfort zone, that's a spiritual matter which needs to be brought before the Lord. As you grow in godliness your comfort zone will broaden to be in accordance with God's will.
The more we grow in our knowledge and gain understanding the more we become like Him. The more we become like Him, the more we will confidently proclaim Christ and His message.
Since evangelism isn't optional, will you obey? Will you share Christ to the unbelieving world?