Is the Cross Really Redeeming?

If the cross redeems, then there's nothing and no one that can prevent those for whom jesus died from being saved. And it is the basis of the assurance our sins are truly, truly forgiven. Not just the possibility of forgiveness, but actual forgiveness, irresistible grace. We have to be effectually called by the holy spirit, the perseverance of the saints,. a promiser that that which god has begun, he will complete unto the day of jesus christ.