There is no contradiction. When you drive a car, accidents happen. This doesn’t mean that you don’t take every precaution to prevent them. Our nature may be inclined towards sin, however, we should try our utmost to prevent accidents and take necessary precautions. Some points to help one understand:
1. The Prophets are sinless, yet they still sought forgiveness – why? There are different levels of sin, mis-steps and heedlessness. We should all at least not engage in Al-Kaba’ir – the Major Sins.
2. The purification of the body is only the 1st stage – so preventing the body from sinning doesn’t mean you’ve become sin-free as the Mind and Heart may still be sinning (e.g. Thinking evil about others and being Ungrateful).
3. Allah azzawajal loves those who turn back to Him in repentance. Allah azzawajal does NOT love those who persist in sin and transgression against Him. There is not virtue in ‘sin’, only in turning away from it.