The church preaches eternal life, which is defined as a ticket to heaven. It also proclaims a relationship with God that is perpetually broken off because God abandons you whenever you haven't confessed every last sin to Him.
The gospel proclaims the sin of the world is taken away.
The church preaches you have to turn from your sin to be saved.
The gospel proclaims freedom.
The church preaches obligation to not sin.
The gospel proclaims the burden of sin, guilt, & shame removed.
The church preaches the burden of sin increased because now God convicts you of your sins (convict which means declares guilty, condemns) & counts all "disobedience" against you.
The gospel proclaims "Whoever trusts in Jesus will never be put to shame."
The church preaches shame over sin (making you feel guilty) as God's primary discipline.
The gospel proclaims "your sins & lawless deeds God will remember no more"
The church preaches all of your sins & lawless deeds will be played on a big screen in heaven to embarrass you in front of everyone you've ever known.
The gospel proclaims the perfect sacrifice of Christ has cleansed & purified us forever so we no longer have to be conscious of sin (counts sins/label things as sin).
The church preaches you must be constantly conscious of sin by measuring your commitment (performance). You should also always be labeling others actions as sin & judging them for it out of fear you may be contaminated by them.
The gospel proclaims you have died to sin once & for all time.
The church preaches you are so alive to sin you must distrust every thought of your sinful heart & fear that anything perceivable as sin can ruin your witness & corrupt you as a person.
The gospel proclaims God no longer counts the world's sins against them.
The church preaches we have to convince the world to stop sinning against God because that is the only way He'll hold back destroying them in His anger.
The gospel proclaims God does not charge Christians with sins.
The church preaches the Holy Spirit's primary job is to charge Christians with sin.
The gospel proclaims Jesus came to put away sins by the sacrifice of Himself.
The church preaches Jesus came to forgive you of your sins over & over & over again. But He only forgives you if you feel really bad, list them to Him in prayer, & promise to never do them again.
The gospel proclaims the law of Moses is over so you don't have to worry about keeping or breaking laws anymore. God leads you by the Spirit not by pre-written rules.
The church preaches you are sinning virtually every moment of your life because you aren't constantly keeping the two greatest laws, which are to love God with all you are & love your neighbor as yourself.
The gospel proclaims Jesus freed His people from sin.
The church preaches the only way to be free from sin is to be perfect in action, in motive, in thought, in emotion, & in physical impulse 100% of the time for the rest of your life.
The gospel proclaims Jesus broke the power of sin, ending its ability to master us & control us.
The church preaches sin is more powerful than Jesus. It can instantly break your fellowship with Him to where He has to immediately abandon you. Every time you sin you are no longer right with God regardless of how much love, forgiveness, & shed blood Jesus has had for you. Some churches even say you can become "unreborn" when you sin, ripping you from your Father & putting you in immediate danger of eternal hell.
The gospel proclaims because Jesus raised again to life we, His people, are not in our sins.
The church preaches you can be in sin if you commit a particular sin too many times in a row without confessing or promising to stop (repenting) in between. How many times in a row? No one is sure so just consider yourself in sin if you've done any singular thing you would calls sin & haven't apologized to God & promised to never do it again.
The gospel proclaims in Jesus there is no sin & you are in Jesus.
The church preaches you can be in sin & in Jesus at the same time.
The gospel proclaims trust (faith/belief) in Jesus makes us truly righteous forever.
The church preaches faith in Christ only makes you positionally righteous, meaning you aren't really righteous in any way God just puts an asterisk next to your name so he can remember to lie to Himself & pretend that you were righteous so He can let you into heaven. He'll only treat you as righteous after you get to heaven. The rest of the time He'll focus almost exclusively on your sin, guilt, & faults to correct you because you are only a valuable person when you are behaving perfectly.
The gospel proclaims God loved us even when we were dead in our transgressions and sins & saved us by His grace, made us alive together with Christ, raised us up with Him, and seated us with Him in the heavenly places in Christ Jesus. He saved us & did all these things so that in the ages to come He can show us the surpassing riches of His loving, favor, & grace in kindness toward us in Christ Jesus.
The church preaches God loved us even when we were dead in our transgressions and sins & saved us by His grace but now that we've been saved even the smallest conceivable sin will make Him stop treating us with kindness & love & start abusing (called chastising/disciplining) us for our own good to make us "like Him." "Like Him" except we aren't allowed to guilt-trip people, be unforgiving towards them, abandon our own children when they do any single thing wrong, record everything someone has done against us so we can show them the list on their death bed, or focus almost exclusively on the sin & failures of someone else so we can chew them out about them.
I hope it is obvious to you that what the gospel proclaims is indeed good news & what the church preaches is bad news.
[If you have a problem with me using the word "church" in a negative sense see this post.]