As the disciples went out on mission, without Jesus for the first time, He explained the dangers which they would face in the future (after He had gone back into heaven). In the same way that Jesus would be arrested and beaten, so would they. But, despite that, they must not be naive; but neither should they step back from the mission of making Christ known.
 
The hostility which believers would face was not because of themselves, but because they identified with Jesus: the Son of God, the Creator of the universe, the King of kings and Lord of lords. Powerful people (or those who like to think that they have control over their own lives and the lives of others) would feel threatened by such an ultimately superior Ruler. They would want to punish anybody who submitted to Him or encouraged other people to do the same.
 
However, the disciples should not worry about what to say or how to defend themselves. God would personally put the right ideas into their heads and the right words into their mouths. He would arrange for them to speak the truth about Jesus, and their relationship with Him. Under Roman law they had a right to speak in their own defence, but God would use that opportunity to announce the gospel to the top authorities (as the Apostle Paul did in Acts chapters 21-26), so that the leaders in society might hear the truth about Jesus - and some were converted.
 
Whenever you are asked to explain your Christian faith, do so clearly and gently. Be ready to speak - not in your own defence but to proclaim Jesus. And yet fear is very common, holding us back from ministry and mission. Fear is one of Satan's tools to stop us. But the Holy Spirit is given to make us bold (Acts 1:8) to speak up about Jesus, so there is no reason to be afraid. The Spirit is always with us and always knows the best thing to say about Christ to the people around us. Trust Him. Let Him inspire you and shape your words with potent truth (Isaiah 49:2). However high the accusation against a believer goes, that is where God is determined that the truth about Christ should be heard.