Dedicating one's life to religion is a major life event for a priest. Preparing for life in the clergy can be tough and stressful, and achieving ordination is a major accomplishment. Choose a gift that honors the priest's life decision and can help him be successful within it.
Priests use all kinds of books to help them prepare sermons and learn how to help others through their spiritual journeys. Choose a book that is within the priest's denomination, such as a book of daily devotions. Alternatively, select a biography of an important figure in the priest's religion. You could also give a work written by a scholar that could give your priest insight into a particular aspect of your religion.
If clergy members in your denomination are permitted to drink wine, choose a nice bottle for him. You could also create a gift basket with a bottle of wine and a selection of gourmet cheeses or chocolates.
In lieu of a gift, give a donation to a group within the priest's religion. You can give money to his congregation. Or you can donate money to a religion-based charity, such as a group that feeds the hungry or takes care of children.
Maybe the new priest will have an office where she will counsel members of her congregation, prepare sermons and conduct other business. She will need some items to help decorate the office. Choose a wall hanging for her office, possibly an appropriate religious symbol. You could also choose a practical gift, such as a desk organizer or a calendar.