The Holy Spirit bears witness for Jesus, and we must bear witness too (Jn 15:27). When we witness for Jesus, we will see God open the hearts of many people, and they will give their lives to Jesus (see Acts 16:14-15). On the other hand, in our witnessing for Jesus, we will encounter strong opposition. Some of those putting us to death will even think they are worshipping God (Jn 16:2).
Witnessing for Jesus means telling someone about your personal experience of Jesus' love. Witnessing is very simple. We do it frequently when we bring up how parents, spouses, children, family, and friends love us. The Lord has chosen to make witnessing for Him extremely powerful in proclaiming His gospel to the world. Thus, witnessing is especially threatening to the devil (see Rv 12:11), who vehemently attacks anyone even who even thinks of witnessing for Jesus. However, the Lord has given His witnesses a Paraclete, the Holy Spirit, Who will give power and boldness to Jesus' witnesses, especially when the devil is trying to intimidate them (Acts 1:8). Then, they witness with power to Jesus' death and resurrection (Acts 4:33) and make disciples for Jesus of all the nations (Mt 28:19).
Don't give in to the evil spirit's intimidation. Rather, give in to the grace of the Holy Spirit to witness for Jesus.