Mistakes of David:
1) It was time when kings go forth to battle, but David tarried at home.
This is not the time for us to sit at home. It is time for spiritual warfare. The Bible says that the Kingdom of God suffers violence and the violent take it by force – Matthew 11:12. The time is near for the coming of the Lord. It is not the time for us to build our own kingdom rather than plundering hell and populating heaven. Jesus said "watch and pray lest you enter into temptation". - Matthew 26:41. These are the days believers must watch and keep praying. We ought to pray without ceasing. - 1Thessalonians 5:17
2) Looking at the things he should not: Matthew 5:28 - Jesus said "If you look at a
woman with lust in your eyes you have already committed adultery Jesus said, "If your eyes compel you to sin, pluck them out." From the terrace, he looked at a woman having bath. She looked beautiful. The things your eyes see maybe beautiful, but deceptive.  Do we as believers, provoke others to sin. Sisters beware how you dress, how you behave and how you appear.
3) Knowingly sinned against God: God has given us the conscience to know what is right and wrong. If we sin willfully, there remains no sacrifice for our sins -
Hebrews 10:26. David committed adultery. A  man after God’s heart, yet he did
such an unholy act. When you drift away from God, you are caught up with the things of the world, then it is very easy for you to fall into sin.
4) Sin will find you out: David committed adultery with Bathsheba and thought nobody knew about it . After some time Bathsheba sent a word to David, saying she was pregnant. When you sin and think nobody knows about it, that is the time your own sin will find you out - Numbers 32:23. Sin is never barren. It will conceive and give birth to death - James 1:15. Many times we sin and behave like hypocrites. Our sin will reveal who we are and bring fear into our lives. To cover our sin rather than repenting, we begin to manipulate. That is what David did. A man after God’s heart became a master manipulator. This is what sin can do in one’s life. Ways David manipulated: (a) Sent for Uriah, so that he may go home and sleep with his wife and thus things could pass off. Uriah didn’t heed to it. (b) Got Uriah drunk, so that when he goes home, irrespective of whether he sleeps with his wife or not, things could pass off. Uriah still didn’t go home. (c) When both his efforts failed, he sent a letter through Uriah himself to Joab, telling him to put Uriah where the battle was fiercest, so the enemy could strike him. There are many Davids who may have killed Goliaths, yet killed many innocent Uriahs in their own fellowships. In these last days beware of sin because Christ is coming for a church which is without blemish, spot or wrinkles.
Conclusion: David made somebody’s wife his own and accomplished his plan. We too may accomplish anything and everything, but if the motive is wrong then the Lord is displeased (read chapter 12 of 2 Samuel to know the consequences). Let’s repent and turn to the Lord, so that he may have mercy on us - Psalm 51:10
1 Cor 15:58 says “Therefore, my dear brothers, stand firm. Let nothing move you. Always give yourselves fully to the work of the Lord, because you know that your labor in the Lord is not in vain”. A day is coming when everything we have done in the house of the Lord will be rewarded.