There is more than one discussion on this site dedicated to proclaiming His Mercy (perhaps all of them, in one or more way?). The purpose of this one deals with aspects in relation to specific little problems especially new-born believers might very much so relate to: Is there any limit to His Mercy?
Even one of His Newbornes might say, upon having a foundation of Knowledge of the message of our Master, Yahushua, "of course not".
"Ask, and it shall be given you; seek, and ye shall find; knock, and it shall be opened unto you: For everyone that asketh receiveth; and he that seeketh findeth; and to him that knocketh it shall be opened. Or what man is there of you, whom if his son ask bread, will he give him a stone? Or if he ask a fish, will he give him a serpent? If ye then, being evil, know how to give good gifts unto your children, how much more shall your Father which is in heaven give good things to them that ask Him?"
-Matthew 7:7-11
He Clearly communicates to us, also, that even our very best on our own are but filthy rags. His Believers do not simply get a knack for behaving, or become sinless by deep and thoughtful meditation.
However, there are those moments, especially when we are face- to-face with our own sin and temptations, when we might let our pre-conceived notions get in the way.
Have you ever messed and...well...know you messed up? You go on your kness, and pray to YHWH, asking for forgiveness in the Name of Yahushua Messiah. You remain on your knees, say you will trust in His Spirit to help you not give in to temptation (in whatever form it shall come in)...and don't quite "feel" right about it yet? Almost as if...you have not "proven" to Him the dephs of your sorrow? Let us keep in mind:
But when ye pray, use not vain repetitions, as the heathen do: for they think that they shall be heard for their much speaking. Be not ye therefore like unto them: for your Father knoweth what things ye have need of, before ye ask Him."
-Matthew 6:7-8
Consider:
"Then came Peter to Him, and said, Master, how oft shall my brother sin against me, and I forgive him? till Seven times? Yahushua saith unto him, I say not unto thee, Until seven times: but, Until seventy times seven."
-Matthew 18:21-22
It should be obvious that "seventy times seven" refers not to a specific value, but to as much as forgiveness is genuinely requested. If He commands His children, wretched sinners, to forgive their neighbor without limit, can we not expect such Mercy from YHWH?
No matter how long we have been in the Faith, our insecurities and emotions try to bruise our faith.
Glory be to YHWH, the Only true Elohim and Maker of the heavens and the earth, whose Kingdom shall Never end.