You believe that there is one God. Even the demons believe that-and shudder. It is of course true that a birth will never occur where there has been no conception, but it is equally true that it is impossible for life to flourish if there is no birth. Birthdays are used as the formal marks and measures of people's lives even though the moment of conception is often recognized as the beginning of life. Quite literally that may have been the case, but this is not our usual way of reckoning life.
Birth is the defining moment of our lives.
Baptism is the visible expression of an invisible process by which God uses his message to touch our hearts and call us by faith into his family. Birth does not create life. It simply brings forth the life that was previously conceived. Birth completes the process that began at conception. Baptism does not create life, but simply finishes the process begun by the Spirit when one came to faith.