Another passuk which is brought in regard to Elul is ומל ה' אלקיך א'ת ל'בבך ו'את ל'בב זרעך Hashem will circumcise your heart and the the heart of your children.
The heart, which is what feels, what understands, what has the ability to recieve and contain exalted feeling of holiness and closeness to Hashem, is stopped up, cold, and indifferent. Teshuvah is akin to the knife used by a bris milah, which removes the "foreskin" of the heart and its "blockage". It returns a berson to being a living creature, with feeling and understanding, not only in material things, but also, and especially in matters of spirituality and holiness.
Before one does teshuvah, it is as if one doesn't exist, as Chazal say, it is better for man not to have been created than having been created. But when one comes to purify himself and to Teshuvah, he is then preparing himself to have an existence.
In Yoma לח: לט we find an interesting Gemara. Someone who comes to Teshuvah is helped. He is likened to someone who comes to buy a sweet smelling oil, and is told to wait while the storekeeper brings it, in order that they may both enjoy from the sweert smell.
A person who enters the world of Teshuvah may feel deep inside, that he has no existence. There is no reason for him to be, and that someone like him is better off not being in the world, after realizing the wrong of his actions. Teshuvah, then, is the will to once again have existence, a proper existence, to live a life of meaning. To feel good about being in the world and that there is a reason for his life.
At such a point, like Chazal say, one who comes to purify himself is helped- by being told to wait.
This waiting, the length of time between the wanting to enter holiness until its realization, when a person feels that he is still "on the outside", is a test. Is he fitting "to be"? Should he be accepted? Shall the gates of holiness be opened fr him also?
Someone who does not know about this test may very easily make a mistake and improperly understand the feelings of distance, and to be pushed away from kedusha. Tzaddikim have already revealed to us, that whenever a person enters Avodas Hashem, then the way it goes is that he is distanced, that it appears to him as if he is being pushed away from above. He feels that he is not at all being allowed in to Avodas hashem. But in truth, all the distancing is really a way of bringing close.
A person needs alot of chizuk, not to feel bad, when he sees how much time, even many years are passing, in which he is trying very hard to serve Hashem, and he is still very far, and didn't even begin at all to truly enter Avodas Hashem.
Even if he sees that he is still full of materialism and lack of feeling in Yiddishkeit, and lts of confusion, and he feels as if he's not being let to do anything that he might want to do for Avodas Hashem.
Even if it looks as if Hashem is not looking his way at all, and doesn't want his Avodah at all, because he sees how he is constantly screaming outand begging Hashem to help him serve Him, and he is still vey far.
On all of this, a person needs alot of chizuk, not to to pay attention to all of this at all. For in truth, all this being distanced in really a way of being brought close.
The most important part of Teshuvah is the desire to do Teshuvah, the want to rectify, and the preparedness to wait. Even if it appears to a person that he is not progressing at all and that he is "not accepted."
The only way to do Teshuvah is if one accepts upon himself that no matter what will be, he will be strong, and keep on going in Avodas Hashem. Many ups and downs must pass over each and every individual, which is impossible to explain how, especially for someone with a history. Therefore, anyone who has mercy and compassion on his own self, must try with all his might to learn and develop in himself this hischazkus.
For this is the main part of Teshuvah, when one knows and believes that Hashem is always with him, everywhere.
The Yetzer Hara's main weapon is truth falsehood. At first he tricks a person into sinning, and then afterwards when he wants to do Teshuvah, he knockshim down and puts into his mind how he is far, and Hashem is not intersested in him anymore, and its impossible to come back. But the truth is Hashem rest with us even in our Tumah (Vayikra 16:16).
This is what Moshe learnt in the fourty days that he was on Har Sinai after the Egel, and Tzaddikim teach us this again every year in the days of Elul: Hashem is with us, with each and every one of us. even with the greatest sinner in the world. And as long as person keeps this in his mind and reviews this in his heart, he for sure has hope.
This is knife through which we need circumcize our hearts: the faith that for every single one of us, whoever it may be, there is hope. And if we'll gird ourselves with patience and continue to want and to try to enter the gates of Kedusha,we will certianly enter.
Adapted from Rabbi Erez Moshe Doron's book, למעלה מן הזמן