'But thanks be to God, who gives us the victory continually (present tense) through our Lord Jesus Christ.'
But now all is changed. Through our Lord Jesus Christ, and His death and resurrection we are delivered. We are being given victory continually, victory over sin now, and finally the victory over death that Christ has accomplished. When the Law condemns us we point it to Jesus Christ. ‘You have sinned,' thunders the Law. ‘Christ died for our sins,' we reply, ‘and the sting of death has been sheathed in Him. And He has been raised from the dead. Thus do we know that His sacrifice of Himself was accepted.' God has given Him, and is giving us, the victory, so that even as we die it is in hope of the resurrection.
And that victory will finally be fully established at the resurrection. Then death will be conquered. It will be no more. And it is all due to Him. It is through God, to Whom we give thanks, and through our Lord Jesus Christ, that we are given the victory, the final victory of everlasting life in all its glorious perfection.