What is sin?

Doesn't baptism wash away all sin?

Since nobody's perfect, who can judge me of sin?

Sin is the "transgression of the law" (I John3:4). This means that whatever God's law is on any matter, to do otherwise is to commit sin.

When one is baptized they have acknowledged the repentence of sin. This means that the person is no longer to live in a sinful manner.If one has not fully repented of sinful activity, baptism does not wash it away.

One is judged by one's actions relative to the scriptures. We have to apply the scriptures to our actions to determine "whether we be of the faith".