"The baptized have become 'living stones' to be 'built into a spiritual house, to be a holy priesthood' (1 Peter 2:5). By Baptism they share in the priesthood of Christ, in his prophetic and royal mission. They are 'a chosen race, a royal priesthood, a holy nation, God's own people that [they] may declare the wonderful deeds of him who called [them] out of darkness into his marvelous light' (1 Peter 2:9)."
-Catechism of the Catholic Church #1268
Lack of knowledge does not excuse us from sharing our faith. Even if we do not have Scripture passages memorized, even if we do not feel as knowledgeable about our Faith as we'd like, each of us does know about our own experience with Jesus Christ. A most effective way to evangelize is simply to share our story.
Sharing our own personal stories of God's action in our lives simply means we tell others about what God has done for us -- His wonderful deeds-- and how He called us out of the darkness of ignorance and sin and into His marvelous light of grace and knowledge.
How is God calling you to share your own personal story with someone today?