"The Church" is a very broad concept - there are many 'flavours' of Christianity - and there are many non-Christian Churches.
However, almost one thing is central to them all - a Church defines sin for its followers. There are few things which are universally regarded as 'sinful', but yet each Church feels that the things it defines as sin is a universal.
No, it is not sin. You cannot sin by not doing they play unless God is telling you to do it.
The christian church blieves that all have sin, it also believes the wages of sin is death. And that sin was washed with the blood of christ on the cross for all mankind.
no
Sin.
Not going to mass on Sundays or holy days is considered a mortal sin in the Catholic Church.
No church can forgive sin. No vicar, priest or whoever can forgive sin unless that sin was committed against that person. When one sins against God then only He can forgive.
to get holy and have no sin
Is it a huge sin to stop being a nun? Of the Roman Catholic Church? No. It is not a sin at all.
Members of the Church of Jesus Christ of Latter-day Saints (the "Mormon" church) do not believe that being human is a sin. They believe that sinning is knowingly disobeying God.
Sin which is selfishness.
No.
No, it's natural.