When Paul says that we walk by faith and not by sight, he had good reason for saying that. He had no physical evidence that he was doing God’s will. He was beaten, put in prison, shipwrecked, and on and on.
This is a stark contrast to the way God had dealt with Israel. If they were walking in God’s will, the nation was blessed. But if they weren’t walking in God’s will, the nation was cursed.
Today the only evidence we have that we are walking in God’s will is faith in the scriptures that He gave us.