By You must have spiritual conversations with unbelievers. That is, in most simple terms, evangelism.
Evangelism doesn’t require a Master’s degree in theology or an unusual sharpness in Bible memorisation; simply speak of spiritual things in your everyday conversations.
Think of Peter and John, the great Apostles, whose evangelising of the lame man was a simple ad-hoc money-to-God’s-power transition (Acts 3:2-8). Or how about Philip, who certainly didn’t study beforehand for the rather un-forseen change of events with Simon the Sorcerer. Simply by pointing to the heart amidst all the external hype, he was able to show Simon his need for the Gospel (Acts 8:20-23). One of my favourites is Cornelius who invited his neighbours and friends to a home Bible study with an external speaker. Sometimes a hospitable spirit is the simple origin of the famous evangelistic meetings (Acts 10:33). Or how about a true Christian worshipping spirit in spite hardships? When in prison, sing!, you might just be the instrument of turning your enemy into a saint (Acts 16:25-34).
Many more stories like these are found in the book of Acts. No wonder the church grew so much in those beginning years!
If you want the world to know Jesus, then each one of us will need to start telling the world about Jesus. Praise the Lord publicly for His goodness shown to you. Help sinners see their sin as their biggest problem. Use your home and resources for people to be exposed to the Gospel message. Exploit your trials for God’s message of salvation.
Whatever you do, do all to the glory of God (1 Corinthians 10:31).
Be in a habit of talking about God’s work in your life, not in a superficial, charismatic, ecstatic way, but with depth, sincerity and purpose.