With the sanctifying grace made possible by Jesus sacrifice on the cross we would still be in the same position as the pre-christian Jews. However, penance is our opportunity to participate in our healing and in the healing of the church. As Paul says in 1 Corinthians when one part of the body suffers the whole body suffers. When one christian sins the whole body of Christ is effected. Jesus doesn't need our participation in the work of salvation for it to be efficatious but he welcomes our addition given in love.
Nothing done out of love is useless or without merit.
For it is by love that we unit ourselves to God. You must register with this board before submitting follow up messages. In fact I have asked for forgiveness for things and not felt forgiven. However I have been taught that this feeling of guilt for something that I know I have already asked for forgiveness for is not from God. Satan likes to keep us feeling like we are still unforgiven because he keeps us trapped that way from having our victory in Jesus.