Acts 23:1

"Paul looked straight at the Sanhedrin and said, 'My brothers, I have fulfilled my duty to God in all good conscience to this day.'" NIV translation

Paul opens this first court appearance by telling the leaders that he has a clear conscious as he has done what God asked him to do.

We, like Paul, must understand that we answer to God as we are His servants because we love Him.

Acts 23:2

"At this the high priest Ananias ordered those standing near Paul to strike him on the mouth." NIV translation

The high priest didn't like what Paul had to say and so he ordered that Paul be slapped in the mouth. We may ask ourselves why Ananias took such offense to what Paul said but it really comes down to power. If people know that they have freedom in Christ and answer to God directly instead of to an earthly priest, that priest will lose his power and in many cases wealth. The same is true today in many cases and was condemned by Jesus in the letters to the churches (see Revelation 2:6) when he spoke of the practices of the Nicolaitans.

Acts 23:3

"Then Paul said to him, 'God will strike you, you whitewashed wall! You sit there to judge me according to the law, yet you yourself violate the law by commanding that I be struck.'" NIV translation

This is the same type of thing that Jesus said to the teachers of the law in Luke 11:37-52. A whitewash is simply like a cheap paint on the wall as it makes the outside look good for a while but can hide its supporting structure. There are people like this even today as they say the right "church phrases" but it is all talk and there is no faith behind it to put the words into action. This is also what James was warning about in his letter to believers (see James 1:19-27).