“‘…And I will take you one from a city and two from a family, And I will bring you to Zion.’”
‭‭Jeremiah‬ ‭3:14‬ ‭NASB1995‬‬
We have often considered this verse as a promise of the new covenant church, and a picture of God’s desire to place the lonely in families. The passage goes on to another wonderful promise, of the anointed leaders who will help those whom He brings to Zion, the church:
Then I will give you shepherds after My own heart, who will feed you on knowledge and understanding.”
‭‭Jeremiah‬ ‭3:15‬ ‭NASB1995‬‬ 
To Whom Is The Promise Given?
It surprised me to notice that at the beginning of the verse, these glorious and treasured promises are given to “faithless sons,” whom the Lord is calling to repentance through the prophet Jeremiah.
“‘Return, O faithless sons,’ declares the Lord; ‘For I am a master to you…’” is how the very same verse begins (3:14). 
It surprised me because of the subtle tendency to think that God’s promises are for the perfect. They are not. As Jesus said, “It’s not the healthy who need a doctor” (Mark 2:17). This continues to be “good news” to me, as I come face to face with areas of faithlessness in my own life. 
And cherished promises of the new covenant are no exception: they’re given to the undeserving. This is cause for rejoicing! Even if you are “faithless,” there’s a promise in the Bible for you.
It is no mediocre faithlessness we are talking about here. This incredible offer of healing and welcome is made to people who have dealt “treacherously” (ie “guilty of betrayal and deception”) with the Lord:
“‘Surely, as a woman treacherously departs from her lover, So you have dealt treacherously with Me, O house of Israel,’ declares the Lord.
‭‭Jeremiah‬ ‭3:20‬ ‭NASB1995‬‬
“You have betrayed Me! You deceived Me!” the Lord says. And yet, He doesn’t spurn us, but rather, He calls us!
Amazingly, there are two more incredible promises given to the faithless in this chapter:
“…‘Return, faithless Israel,’ declares the Lord; ‘I will not look upon you in anger. For I am gracious,’ declares the Lord; ‘I will not be angry forever.
‭‭Jeremiah‬ ‭3:12‬ ‭NASB1995‬‬
Return, O faithless sons, I will heal your faithlessness…
‭‭Jeremiah‬ ‭3:22‬ ‭NASB1995‬‬
Conditions For Fulfillment
As we have learned, every promise in the Bible has a condition. There are two simple conditions mentioned here that are critically important to fulfill. 
“‘Only acknowledge your iniquity, That you have transgressed against the Lord your God And have scattered your favors to the strangers under every green tree, And you have not obeyed My voice,’ declares the Lord.
‭‭Jeremiah‬ ‭3:13‬ ‭NASB1995‬‬ 
And, “Return…” (v12, 14, 22)
The incredible new covenant promises of Jeremiah 3 — that God will not look upon me in anger, that He will heal my faithlessness, and that He will bring me into His church — hinge upon honest confession and repentance. 
Surely how true it is that, “Good and upright is the Lord; Therefore He instructs sinners in the way.
‭‭Psalms‬ ‭25:8‬ ‭NASB1995‬‬
One Word of Warning
The tendency when we acknowledge is to wallow. When we see the magnitude of our treachery, we can respond just like those who received the promise:
Let us lie down in our shame, and let our humiliation cover us; for we have sinned against the Lord our God, we and our fathers, from our youth even to this day. And we have not obeyed the voice of the Lord our God.
‭‭Jeremiah‬ ‭3:25‬ ‭NASB1995‬‬ 
It is possible to read this response and think it honors God. But look at how the Lord responds:
“‘If you will return, O Israel,’ declares the Lord, ‘Then you should return to Me…’”
‭‭Jeremiah‬ ‭4:1‬ ‭NASB1995‬‬ 
The Lord corrects them: “If you’ve heard all this — actually do the returning! Come back to Me!” What I see here is that it’s not enough just to wallow in our acknowledged sin. In fact, wallowing is failure to return!
The precious promises of the new covenant are not given under the condition to “acknowledge and wallow,” but rather, to “acknowledge and return.”
So certainly, we must mourn our sin (Matthew 5:4). But our mourning must result in a joyful return to the Lord. If we are not rejoicing in the presence of God, our mourning has not accomplished the purpose for which God commands us to acknowledge our sin. 
You have turned for me my mourning into dancing; You have loosed my sackcloth and girded me with gladness,
‭‭Psalms‬ ‭30:11‬ ‭NASB1995‬‬
To grant those who mourn in Zion, Giving them a garland instead of ashes, The oil of gladness instead of mourning, The mantle of praise instead of a spirit of fainting. So they will be called oaks of righteousness, The planting of the Lord, that He may be glorified.
‭‭Isaiah‬ ‭61:3‬ ‭NASB1995‬‬