Official Protection
Paul had come to Jerusalem, joining with a multi-national throng of displaced Israelites (Acts 2:5-11) to celebrate the feast of Pentecost (Acts 20:16), knowing that he would encounter hardship for the sake of Jesus, and imprisonment. Although the leaders of the church there tried to reflect traditional religious criticism away from Paul and his team (Acts 21:21-24), his opponents were undeterred. The main protagonists appear to have been men from Ephesus who had seen Paul there (Acts 21:29) and had probably contributed to a public uprising against him (Acts 19:29-31).
And so they spread lies about Paul, claiming that he had taken Trophimus, a Gentile, past the Court of the Gentiles into the Court of Israel (Acts 21:28-29). It was a very serious religious accusation, that Paul had desecrated the temple, successfully fomenting a stampede of people rushing to the temple to seize the apostle. It was a well-orchestrated act of public disorder.
The rioters wanted Paul dead. The common method was by a mob stoning the offender. That required others to get out of the way, but the mob was large, surrounding the apostle in the narrow streets . So they tried to beat him to death. By that time the Roman militia was alerted. A riot must be avoided as Rome could inflict severe penalties on the Governor for allowing public disorder. The commander took swift action in quickly running to the scene with a squad of soldiers. They were in time. Paul's life was saved by the protection of Roman law.
In this narrative, the Lord was in charge. It was His plan for Paul to witness before kings and ultimately Caesar (Acts 9:15). But the fury of religious traditionalists was at boiling point, and Paul needed the protection of the legal system. That is what the Lord was arranging in Jerusalem. From that point on, He safeguarded His apostle through the governing authorities, even though they did not realise they were acting as God's servants. When the Lord wants to protect His people so that they may serve Him, He commands whoever He chooses to keep them safe. So you do not need to fear. As you trust the Lord, He will make sure that you are able to serve Him in safety until your work is done (Psalm 27:1-3).