1- Vetoing it would be against equality. Everyone should have the right to marriage, even if it is to someone of the same sex.
2- Chris Christie has said he does not want the Senate deciding if gay marriage should be legalized, the people of the state should decide. However, in a recent poll, most people in New Jersey voted that they want gay marriage legalized.
3- If he is doing so for religious purposes, he should keep in mind that God loves all people and God wouldn't make the people the way they are unless he loved how he made them. By vetoing the bill, he is taking one of the seven sacraments away from many people. Marriage. If a certain church does not want to marry two gays or lesbians, then it is the church's decision, not the government's.