That is very difficult since the church dogma is based on acceptance of JC as savior, Even an evil man can be "saved" and enter heaven if he accepts JC as savior before death. It teaches you can not get into heaven by good deeds alone. But more to your point there are many instances in their book that mentions

1. knowing people by what they do and not what the profess
   {Matthew 7:16 By their fruit you will recognize them}
2. the rich young man who asked what good deeds he could do to get into heaven and was told to give up his wealth and he refused
   {Mark 10:17-23 ... it is easier for a camel to pass through the eye of a needle than for a rich man to enter the kingdom of God.}
   That brings us to all the riches you accumulate in heaven by sacrificing here on earth, which is what I was taught that many churches now have turned their back on.
   And lastly, my all time fav
3. those that profess the faith but do not follow the FULL premise of the faith: It claims that all those who profess Christian faith should ALSO do good deeds, but nowhere does it say that a good deed doing person can go to heaven for doing good deeds, unless he (an innocent children) are ignorant of the word of god.
   {James 2:14 What good is it, my brothers, if someone claims to have faith, but has no deeds?}

So basically the greatest sin is just denying/defying/ignoring their "god" even after they have told you about him.

I believe that all acts of charity, deep down, are partly based on ego. We want to make ourselves feel good so we do for others. Sure, there's compassion, that goes without saying. But we get a feel good reward. It's too bad that feeling isn't as addicting as opioids.

When I help someone and they say "thank God" I always tell them that God had his chance and did nothing. I am the one who helped you, not God. Then they say "you will be blessed by God" and I say I do not believe in God and I helped you because you needed help not for a reward.

You may be assuming that a religious person, or in your example, particularly a religious Christian can’t have a basic inane goodness. The reason I specified Christian is that Jews don’t have heaven, so there’s no reward and someone who understands will have to explain the complexities of Muslim heaven, so I don’t know how basic goodness affects inclusion or exclusion.
Anyway, bottom line is that even people who subscribe to religion can be good.

To me it doesn't matter who saves the kid from drowning, only that the kid is saved.

I completely agree. religious people have something else morals really where we have our own. quite ironic they often ask about our moral fibre

Religious or otherwise I have respect for anybody that performs an act of kindness for no return or with no caveats involved. I like to think I do all manner of 'nice' things during the course of the day from making someone a cuppa to maybe donating time/money etc but for me it's an end unto itself and I don't keep score. I'm also aware of god believing people who do the same and if they choose to give their god some credit then fine. If it motivates them in the first place is that good or bad? I don't know, it doesn't bother me whether they make the coffee or god does. But it maybe asks the question that we get thrown at us about morals, we get our morals from within us, they get them from an external force, does that not make ours more genuine and human?

I agree, but too many Christians if they are nice because of the reward of heaven or the fear of eternal damnnation, not because it is the right way to live. Most of the best people I have known are non-believers. They don't need a carrot or a stick to be a decent human being

Maybe not for a heavenly reward, but I've known atheist/agnostics to do it for publicity. To me that's just as bad.