Paul's dramatic conversion to Christianity, following his spiritual rebirth on the way to Damascus, did not only astonish the Christians he had relentlessly persecuted in the past, but also his family and friends.
They might have thought he had gone insane, because for what other reason Paul would have given up the life of fame, wealth and comfort he had as a rising star in the Pharisees party in exchange for the harsh, precarious and short life of a Christian?
If anyone knew the condition of life of Christians during the days of persecution, it was Paul, since he had intimate knowledge of the cruelty inflicted upon them.
Paul was fully aware of the life that awaited him as a newly converted Christian. Before his mind's eye must have arisen the specter of being stoned to death, tortured with ingenious devices, beaten senselessly, imprisoned, thirsty and hungry, as he would later recount in 2nd Corinthians 11:23-28.
Yet he was not deterred. Neither the fear of man, nor the fear of death could turn him away from the true gospel he had received from Jesus Christ on the way to Damascus. He was determined, regardless of the danger ahead, to spread the true gospel to all corners of the earth.
In Romans 8:35, Paul expressed his determination to press on in words that could only have been his: "Who shall separate us from the love of Christ? Shall trouble or hardship or persecution or famine or nakedness or danger or sword?" He would allow nothing to deter him from holding onto his faith in God.
From a human perspective, Paul had everything to lose by becoming a Christian: his family, his friends, his prestige and comfort. He would not have put himself in such jeopardy had his mind not been renewed spiritually by the power of faith; opening his eyes to see beyond the material things in this world which are temporary, to the spiritual things in heaven which are eternal.