The actions of one person can have a major effect on a congregation. The example of a strong Christian can encourage others to study their Bibles obey the Gospel and stand firm in the word of God.
But a negative example can deter people from coming to Christ and it can weaken the spirits of our brethren. Our sins not only hurt us but they also hurt those who are closest to us.
Also God does not despise any of us and He does not inflict our suffering upon us.