When God graciously removes the log from your eye, how will you then approach your brother? You will come gently, because that is who God has been to you. Galatians 6:1 gives us the pattern: restore, in a spirit of gentleness, while keeping watch on yourself. The same passage that sends us to help also warns us to guard our own hearts against the pride of thinking we would never fall into that sin.
Love sometimes has to risk peace for the sake of truth, as Dave Harvey observes. Restoring a brother may mean disturbing the peace and saying the hard thing. But you have no business saying the hard thing to anyone until you have first let God say it to you. The difference between a critic and a restorer is not whether they speak; it is the heart and the order behind the speaking.
This is why some of us struggle to be gentle. We are not gentle with others because we do not believe God has been gentle with us. We carry a skewed picture of a condemning God rather than the God revealed in Jesus Christ, who reconciled us while we were still His enemies. The gentleness we receive is the gentleness we are then able to give.