About 70% of priests and about 99% of deacons are secular Catholics. They are not religious.
Priests who are religious are in a whole different category. They are not secular men. They are consecrated men, not because they’re priests, but because they’re in vows. There are two vows that come into play here that diocesan priests do not make: obedience and chastity.
Through the vow of obedience, the religious gives us his will, desires, wishes, aspirations and lays his life in the hands of the superior and of his brothers. The promise of obedience that secular deacons and priests make only requires them to obey the bishop’s policies. The bishop has no say in their other activities.
Through the vow of chastity, the religious no only promises to be celibate, bur he also commits himself to the common life. The diocesan deacon and priest makes a promise of celibacy, which is a promise never to marry. There is no commitment to community. He has time and freedom to do what he wants.
It’s not the K of C who set the rules for the chaplains. They only define their needs. The superior, if the man is a religious, is the one who decides whether or not his brother will be a member of the Knights.
In the case of the secular clergy, this is not necessary. They do not have to get permission from the bishop. He just needs to be informed.
The priest who is a religious is a religious first and a priest second, that’s the difference.
Fraternally,
Br. JR, OSF