missing birth for Alexander Dunbar from Belfast

[Rosezi]

i am searching for a baptism record for a Alexander Dunbar born in Belfast around 1845. He was a mariner and probably left Ireland around the late 1860s and settled in Liverpool with his wife Margaret who was also a Dunbar, but from Dublin. His father was Daniel Dunbar a  Land Steward. I have no further information on any other family member from Belfast. I have looked on rootsireland and found nothing to match the date of birth. Any help to solve this mystery would be greatly appreciated.

[aghadowey]

It may be that a baptism record for Alexander Dunbar doesn't exist but if such a record survives it might not be available online.

What religion were the Dunbars? What information do you have about the marriage?

[Rosezi]

Alexander married a Margaret Dunbar in 1868 in Birkenhead, Cheshire, they moved to Liverpool and had 4 sons Daniel, Charles, John and William. The children were baptised Catholics, so he may have been a Catholic also, or married a Catholic. His second wife was a Maria Mullen who he wed in 1888. I have lots of info on his life as a mariner, crew lists etc.. but nothing about his life before he came to England