What is the gerund phrase in the sentence, "Bearing is the precious seed of the gospel to others will bring its reward." And what is it used as?
The gerund is formed from the verb but it acts like a noun.
For example, we have the verb "to bring", which can mean "to carry something to someone". The present-participle form of the verb, bringing, can be used as a noun:
Bringing food to the workers was his job.
We call that noun-from-verb a gerund.
The marked infinitive can also be used nominally:
His job was to bring food to the workers.
Both the participle and the infinitive refer to the abstract idea of the verb's action, rather than to the action actually as it happens or is performed at a particular moment by a particular actor:
He crossed the busy street at 5PM.
Crossing a busy street can be dangerous.
To cross a busy street can be dangerous.
In conversation, it is more natural to use the -ing form than the marked infinitive in this role; you will hear speakers using the so-called "dummy it" in combination with the marked infinitive:
It can be dangerous to cross a busy street.