Without the vision of faith, we can easily be tricked by outward appearance. He freely chose to become the protector of Mary and has been named the patron of the Church. The vision of faith and the prompting of his heart prompted Joseph to take Mary as his wife. It is with the ears of the heart that we are able to hear the voice of the Bridegroom calling to his Beloved.
Faith is never to be confused with blurry eyed naivete.
Joseph was fully aware of the social consequences of marriage to a woman in Mary's condition. Humanly speaking, he doubted he could stand up to the tongue wagging and self-righteousness of small town snobbery. However, sustained by the message of his dream, Joseph changed his mind. Making use of his physical skills and drawing upon his aptitudes of mind and character, he became a co-worker with the Lord and thus became a sharer in the work of redemption. Joseph stood by Mary and helped her parent her son.