If any man sin, we have an advocate with the Father, Jesus Christ the righteous...
1 John 2:1
"If any man sin, we have an advocate."
John does not say, "If any man sin he has forfeited his advocate," but "we have an advocate," sinners though we are.
....it is "Jesus Christ"-Christos, the anointed.
This shows His authority to plead.
The Christ has a right to plead,
for He is the Father's own appointed advocate and elected priest.
He is Christ,
and therefore authorized;
He is Christ,
and therefore qualified.
He declares Himself my substitute and puts His obedience to my account."
Charles Spurgeon