Another word for zeal

In what proportion zeal for the ancient canons and the rights of others, and jealous fear of encroachment upon his own jurisdiction, were mixed in the motives of Leo, it would be interesting to know.
In this process some of the local officials displayed probably an amount of zeal beyond the intentions of the government, but any attempt to oppose the movement was rigorously punished.
With the zeal of new converts they set forth on their new errand very much in the spirit of their heathen forefathers.

What's another word for zeal?