What is the significance of Iago's quote "All seals and symbols of redeemed sin" in Act 2 Scene 3 of Macbeth?

To understand Iago's quote, "All seals and symbols of
redeemed sin," you must examine the complete text surrounding
it:

To win
the Moor, were't to renounce his baptism,
All seals and symbols of redeemed
sin,(330)
His soul is so enfetter'd to her love,
That she may
make, unmake, do what she list,
Even as her appetite shall play the god

With his weak
function.

Iago is saying that
Desdemona has such a way with Othello, the Moor, until she could win his favor if he had
to renounce (to give up by formal declaration) his own baptism, which is a seal and
symbol of his forgiveness (redeemed sin).

Desdemona has
such grace in Othello's eyes until he would renounce (deny) his own baptism, a seal and
symbol of his forgiveness, if she requested it.

Of course,
Desdemona would never ask Othello to renounce (deny) his own baptism. She would never
ask him to deny his faith. "All seals and symbols of redeemed sin" would be referring to
Othello's baptism. To be baptized is a seal or symbol of redeemed sin. Baptism, which is
made publicly known during a baptism ceremony, is a seal or symbol of forgiveness. It is
connected to Othello's faith in God.

Desdemona has
influence with Othello at this point, but she would never ask him to renounce his own
faith. She would never ask him to give up by formal declaration his baptism because his
baptism is a seal and symbol of forgiveness (redeemed sin).

Iago is just making such a reference to show the hold that
Desdemona has on Othello. She does have a strong hold on his heart at this point.