Updated: Feb 24, 2021
This is one of the common questions put to Christians by Muslims such as Zakir Naik (see video below). This, of course, is asked in ignorance as the old testament laws on diet are no more applicable for believers of Jesus Christ. Faith in Christ has given us freedom from the laws that were given to Israel. Jesus came as a Jew and before his sacrificial death at Calvary, the laws have to be fulfilled by him and he lived sinless with perfect obedience to the law. Islam adopted the dietary laws given to Moses and since Muslims are not in covenant faith in Jesus, they follow the laws which Islam has adopted from the mosaic laws. In contrast, under the New Covenant, Christians are free from such dietary and ceremonial laws. If a Christian chose not to eat pork, it is his/her preference or as tradition and not mandated by religious law.
This paper (PDF file below) discusses the issue. Please see the two videos below.