God forgives - and then lets us reap what we have sown.
This is true by the experience of all of God children. David was told that his sin with Bathsheba had been put way by God; his sin was "put away", but the consequences were to last all his life. His house was to be always troubled. Our flesh is often destroyed in order for our spirit to be saved (Psalm 38} We are sowing our future every day. And that which we reap will not always be pleasant. It may often not seem good - but it will be, unknown to us. Uneventfulness is deceptive, however. Sooner or later, of our lives will force us to reap.
The uncertainties of life are not really all that uncertain. The law of consequences may wait a long time before finalizing. Reaping what we sow is a law. It is of God. It is not often thought of in that light, but it will function no matter what we think. It could be called the law of "cause and effect", or perhaps some other description. At times immediately after conversion and surrender to God, new Christians are in a euphoric state for a time. Then something occurs that snaps them back into the realization that cause and effect is still operating in their lives. This is sometimes very traumatic - depending upon the nature of the effect. They tend to desire to blame someone. At times, they want to blame God, and feel betrayed by Him. Discouragement sets in, and life troubles begin to resemble their prior life in sin. They say, "but I'm not living that way anymore. Why is this happening, and why do I feel this way?"
Others who do fall back into a sin, or a sinful way of life, God deals with them in a similar way. Paul said he had committed one who had committed a very serious sin, one that was very offensive and such a bad influence on the church, that he had turned such a one over to Satan for the destruction of the flesh, so his spirit could be saved. What Satan did to this person is not recorded in scripture. Undoubtedly, it involved his body in some way. Again, there is the reaping of what was sown. Only in this instance, it was called for by the Apostle Paul (1 Corinthians 5:3-5).
With most Christians, God just allows the "natural" consequences of our lives to bring about the unpleasant harvests in our lives. Therefore, when one becomes a believer, some things may not change very much. Troubles continue to plague them. Like the lyric to a gospel melody says, "troubles trouble us all".
So if you are new in your faith in Jesus Christ, and you are still being troubled with troubles, do not jump to the conclusion that God is punishing you for something committed after your conversion. Probably your troubles are just the fruit of what was sown before you came to Christ. God allows these things in all our lives. Some are severe. Some are less so. Of course, if we add to the transgressions of the past new ones after coming to Him, you can expect an additional effect from the present cause.
But the whole process is for your good. Be assured, you have been forgiven all your sins - yes, ALL. Those in your past, those of today, and those of tomorrow. Those sins of today and tomorrow, that we are convicted of by the Holy Spirit must be repented of, even though they are already paid for by the cross (1 John 1:9). This is why a constant, humble attitude of repentance is necessary. You will grow more and more your sinless with each passing day - although the reaping of your past will continue. However, remember, each day with Jesus Christ produces less and less sin, that means one more day farther away you become from reaping the unpleasantness of the past. Slowly but surely you will outdistance those things of the past. Your reaping of the unpleasant consequences will be less and less. More and more you will be reaping good things - plea sent, even the exhilarating things of God. This is the core of what Peter wrote: "But grow in grace, and in the knowledge of our Lord and Savior Jesus Christ. To him be glory both now and for ever. Amen."
God is allowing all these things in your life for good. God is a God of all grace and mercy. At the same time, He is a God of perfect justice. Some day the whole world will understand and believe both sides of His nature, His holiness, and His perfect understand. All of this in you life now is about showing His perfect love for you. He wants you to be with Him forever! So do not despair! He is for you, not against you. That being true, what can really be against you? All in your life now is designed to do you good!
"For I am persuaded beyond doubt (am sure) that neither death nor life, nor angels nor principalities, nor things impending and threatening nor things to come, nor powers, nor height nor depth, nor anything else in all creation will be able to separate us from the love of God which is in Christ Jesus our Lord." - Romans 8:38-39 (AMP)