When people want to sin they usually come up with some excuse. That in itself should show you that it is a sin. Many people say "everybody's doing it", while others use the excuse "nobody will ever know". But, the most believable lie that many people say is "one time won't hurt".
But, that's the danger of sin- one time CAN hurt.
When David committed adultery with Bathsheba, he didn't realize how much the price of that sin would be. The baby died, his daughter raped by his son, her brother murdering the rapist and then trying to take over the kingdom (which led to that son's death) was all part of the price for that one sin.
But, most people don't look much further than that. Did you know that David paid even more than just what was mentioned above? David wrote a Psalm after Nathan the prophet came to him and let him know that the sin wasn't ignored by God. In this Psalm, he says some things that show us how this sin affected him personally.
It hurt his cleanliness. In the Old Testament, you had to keep the law to gain entrance to Paradise. If you died without having sacrificed an offering to have that sin covered you went to hell.
Psalm 51:1-2- Have mercy upon me, O God, according to thy lovingkindness: according unto the multitude of thy tender mercies blot out my transgressions. Wash me throughly from mine iniquity, and cleanse me from my sin.
David also hurt his mind. Have you ever had something just keep coming to mind no matter how hard you try to push past it? Satan loves to throw our sins in our faces. David was forever haunted by this remembrance.
Psalm 51:3-7- For I acknowledge my transgressions: and my sin is ever before me. Against thee, thee only, have I sinned, and done this evil in thy sight: that thou mightest be justified when thou speakest, and be clear when thou judgest. Behold, I was shapen in iniquity; and in sin did my mother conceive me. Behold, thou desirest truth in the inward parts: and in the hidden part thou shalt make me to know wisdom. Purge me with hyssop, and I shall be clean: wash me, and I shall be whiter than snow.
He hurt his own heart and his spirit. His joy was gone. There was no comfort from the Lord while he was enduring the consequences of his actions. There was fear and dread and wondering if he were to pay not only in this life, but also in hell for eternity.
Psalm 51:8-12- Make me to hear joy and gladness; that the bones which thou hast broken may rejoice. Hide thy face from my sins, and blot out all mine iniquities. Create in me a clean heart, O God; and renew a right spirit within me. Cast me not away from thy presence; and take not thy holy spirit from me. Restore unto me the joy of thy salvation; and uphold me with thy free spirit.
David also suffered some consequences in his body. Sexually transmitted diseases are not something new. They've been around for a very long time. And, it takes just one promiscuous moment to contract an STD for a lifetime!
Psalms 38:11- My lovers and my friends stand aloof from my sore; and my kinsmen stand afar off.
Probably the most lasting hurt was that of his testimony. From then on, people talked about the man after God's own heart with an addendum.
I Kings 15:5- Because David did that which was right in the eyes of the LORD, and turned not aside from any thing that he commanded him all the days of his life, save only in the matter of Uriah the Hittite.
This one time became a public lesson to the world. Everyone for all eternity will know about the one time David committed adultery.
Psalm 51:13-19- Then will I teach transgressors thy ways; and sinners shall be converted unto thee. Deliver me from bloodguiltiness, O God, thou God of my salvation: and my tongue shall sing aloud of thy righteousness. O Lord, open thou my lips; and my mouth shall shew forth thy praise. For thou desirest not sacrifice; else would I give it: thou delightest not in burnt offering. The sacrifices of God are a broken spirit: a broken and a contrite heart, O God, thou wilt not despise. Do good in thy good pleasure unto Zion: build thou the walls of Jerusalem. Then shalt thou be pleased with the sacrifices of righteousness, with burnt offering and whole burnt offering: then shall they offer bullocks upon thine altar.
God promises forgiveness of our sins when we confess them to Him.
I John 1:9- If we confess our sins, he is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness.
But, forgiveness will not take away the consequences of sin.
Galatians 6:7-8- Be not deceived; God is not mocked: for whatsoever a man soweth, that shall he also reap. For he that soweth to his flesh shall of the flesh reap corruption; but he that soweth to the Spirit shall of the Spirit reap life everlasting.
Sin does hurt. Sin leaves a lasting impression on our lives and the lives of others. One time can bring in a whole shipload of momentous payments that you will have to endure.