Who among us remains sinless after Baptism (the washing of regeneration)?
None of us remains sinless and all men sin every day of their lives.
By the indwelling Holy Spirit, we sin less and less as we are sanctified, by His will.
Mercifully, Christ's atonement for our sins is credited to our account. We are declared righteous before God not through our own efforts or obedience or righteousness, but through Christ's justification of us; through His work, His obedience; His righteousness.
This is pretty basic Christianity 101.