It is helpful to know because you must realize it is God who saves people. Remember, the gospel is preached after sin is made known. Because the sinner cannot come to God on his own, he must be convicted of his sin, and thus be made aware of his need for salvation. The conviction of sin is beyond our control. Prayer is essential in witnessing It is, then, vital that you pray and request God to convict as well as save.
Prayer is an essential part of witnessing.
When you witness you must pray. The work of the Holy Spirit is essential in salvation. Without the Holy Spirit we would be like ships without rudders, unable to live as Christians and certainly unable to witness effectively. Sinners come to Jesus to have their sins cleansed. They do this after they discover their guilt before God.