Redcrose goes through the healing process which includes ashes, sackloth and fasting to purge himself of sin. This is misleadingly similar to the senseless penances Corceca did in Canto 3, the difference of course being that Catholics are not enlightened by true faith and perform these acts mindlessly, while Redcrosse’s penance is firstly, directed towards improving his soul through mortifying his body, and secondly, it is accompanied by deep spiritual contemplation and remorse. (Spenser does a very rigorous tit-for-tat analogy between all the sinful figures we’ve met earlier and all the virtues in the House of Holiness, and there’s a whole critical industry dedicated to tracking all these analogies down.) So Penance disciplines him with an iron whip, Repentance pricks his heart and Remorse bathes his wounds in salt water (of his tears). He groans throughout the process very loudly and Una tears her hair out listening to it, but she knows it has to be done.
After the penance is completed, Una takes Redcrosse to Charissa, who has just risen from her last confinement. Charissa is the allegory of Christian love (agape) and it’s said explicitly she hates Cupid, that is sexual love (eros). Charity is thus strangely both physical and asexual – her breasts are always out but only so that she can feed her multiple children, illustrating the neverending love. She is swathed in yellow robes, which supposedly stand for gold, the symbol of perfection, wears a golden tiara and is accompanied by a pair of turtledoves. She instructs Redcrosse, at Una’s behest, about love and good deeds and calls on the help of a grave old lady called Mercy to lead him.
(An image of Charity from the famous work Iconologia by Cesare Ripa, roughly corresponding to Spenser’s description, can be seen here.)