You will be in a spiritual war for the rest of your life. God has already won that war for you but you must learn to make the right choices in life. So put on God's armor, bind all evil spirits, pray a hedge around yourself and your family, then pray. You can't lose - God is on your side.
Phil.4 Finally, brothers and sisters, whatever is true, whatever is noble, whatever is right, whatever is pure, whatever is lovely, whatever is admirable—if anything is excellent or praiseworthy—think about such things. Eph.5 Set your minds on things above, not on earthly things.
When you got saved you received a new spirit. That spirit is perfect and wants to please God. However your mind is not new, you have the same mind you had when you were a sinner. And so God says your mind has to be transformed by reading the Word of God Rom.12 Do not conform to the pattern of this world, but be transformed by the renewing of your mind. with the Word of God Satan knows that your mind is still the same so he try's to attack your mind. The battle ground here on earth is for the control of your mind. The only weapon satan has is to attack you thru your thoughts. He tries to discourage you by telling you about all of your failures, sins, wrong choices and bad relationships you have had. He wants to take control of you by controlling your mind. He has no power so he uses deception and lies to try to deceive you.