"Only once did God choose a completely sinless preacher."
No, pastor, you are not without sin and you do fail but the Lord uses you in your weakness to glorify Him. Though there are days the gravity of the call and the sin that so easily entangles may weigh heavy on you, Christ is the true and better Preacher. Even in your failings, Christ is exalted.
"Since then we havea great high priestwho has passed through the heavens, Jesus, the Son of God,let us hold fast our confession.For we do not have a high priestwho is unable to sympathize with our weaknesses, but one who in every respect has beentempted as we are,yet without sin. Let us then with confidence draw near to the throne of grace, that we may receive mercy and find grace to help in time of need."