What is the meaning of Acts 28:21-24?

21 And they said unto him, We neither received letters out of Judaea concerning thee, neither any of the brethren that came shewed or spake any harm of thee. 22 But we desire to hear of thee what thou thinkest: for as concerning this sect, we know that every where it is spoken against. 23 And when they had appointed him a day, there came many to him into his lodging; to whom he expounded and testified the kingdom of God, persuading them concerning Jesus, both out of the law of Moses, and out of the prophets, from morning till evening. 24 And some believed the things which were spoken, and some believed not. (Acts 28:21-24 KJV)

William Burkitt’s Commentary

Observe here, 1. The advantage which the apostle had to preach the gospel to these Jews at Rome: they assured him that they had entertained no prejudice against his person; for they had received no letters out of Judea concerning him; neither had any of their brethren that came from Judea spoken any evil of him; yea, they assured him that it was their desire to hear him preach and to understand what he had to say for the Christian religion, (which they call a sect or heresy,) that both Jews and Gentiles did generally oppose and speak against and talk hardly of.

Observe, 2. How readily the apostle complies with their request in preaching to them: time and place are appointed, the people assembled. The great truth defended and approved was this, That Jesus of Nazareth was the true and promised Messiah, in whom all that desire to be saved ought to believe and trust. This argument he confirmed by testimonies out of the law of Moses, and out of the prophets, continuing his discourse from morning until night: so unwearied was this faithful labourer in his Lord and Master’s work.

Observe, 3. The different success of the word preached and the contrary effects which it had upon its hearers:  Some believed the things which were spoken, and some believed not.

As the same sun that softens the wax hardens the clay, so does the gospel have different effects upon those it is preached to; there are some whom no sun will tan, no heat will warm, and no influence will quicken. To some, we are the savour of life to life, to others the savour of death to death: but, blessed be God, if we his ministers be found faithful, we shall be a sweet savour to God, as well in them that perish, as in them that are saved.