The final fruit of the Spirit is self-control. Some Bibles use the word temperance. Concerning this word, A.T. Robertson says,
"Old word from egkrates, one holding control or holding in."
There is wisdom in holding things in. There is a time to be gentle, and a time to be more firm. Sometimes we may feel like we want to jump all over one who is caught in a sin. We may want to lecture, condemn, etc. But Paul says that those who are spiritual are to restore such a one in gentleness. Part of being spiritual is to be self controlled, "holding in" as Robertson puts it.
One who does not control his tongue will bring trouble not only on others, but on himself as well.
"In the mouth of the foolish is a rod for his back, But the lips of the wise will protect them (Prov 14:3)."
Paul says this about our speech.
"Let your speech always be with grace, as though seasoned with salt, so that you will know how you should respond to each person (Col 4:6)."
So when one is caught it a sin, we need to be graciously firm. To be gracious and to be firm is not a contradiction. Often times you will get farther with gracious firmness than with non-gracious firmness.
"The tongue of the wise makes knowledge acceptable, But the mouth of fools spouts folly (Prov 15:2)."
"This you know, my beloved brethren. But everyone must be quick to hear, slow to speak and slow to anger (Jas 1:19)"
Not only are we to be self controlled in speech when dealing with a fallen brother, we also need to be self-controlled in all aspects. Notice how Paul says we are to restore a fallen brother or sister…
"Brethren, even if anyone is caught in any trespass, you who are spiritual, restore such a one in a spirit of gentleness; each one looking to yourself, so that you too will not be tempted. Bear one another's burdens, and thereby fulfill the law of Christ (Gal 6:1-2)."
Those who are spiritual are ones with self-control. Paul says we must be looking to ourselves, so that we will not be tempted by the sins that entrapped our fallen brother or sister. This takes a certain level of humility to recognize that we can be entrapped in the same way our fallen brother or sister has.
So there it is. In order to be effective in restoring a fallen brother, we need to have, "love, joy, peace, patience, kindness, goodness, faithfulness, gentleness, self-control (Gal 5:22-23)"
We should all strive to be more spiritual, and in being more spiritual, more effective at building each other up and helping each other to stay faithful.