While the five points of Calvinism (TULIP) were coined after Luther and Calvin lived, we know that Luther believed in Total Depravity, Unconditional Election, Irresistible Grace, and the Perseverance of the Saints. He was moderate in his understanding of Limited Atonement.
But that's no surprise. He was a first generation reformed, often still hamstrung by the papacy which he was leaving.
Catholics, Orthodox, Lutherans, Anglicans, Methodists, Pentecostals — all to some extent or the other acknowledge of mortal sins that can cause us to lose salvation (Quix -- pentecostals of course believe that sins against the Holy Spirit will not be forgiven, right?) at least in some form.
Your are mighty confused about what Protestants believe.
We do not divide sins into "mortal" and "venial" sins. Sin is sin. What is a mortal sin to the Roman Catholic? Is it murder? Protestants believe even murder can be forgiven the Christian. Don't Roman Catholics?
We also know about the "unpardonable sin" which is most likely denying the Holy Spirit.
I would worry if I were a Roman Catholic because Rome seems to "deny the Holy Spirit" over and over when it substitutes Mary and its church hierarchy in the rightful place of the Holy Spirit.
Repent. God forgives a contrite heart.
As far as doing any of those things after one is saved, yes, we still do commit them to some degree. Jesus taught that it was the heart that mattered. To lust after a woman is to commit adultery with her. To hate someone is equivalent to murder.
Sin is born in the heart long before it is expressed in the actions.
God knows we are still going to sin and has made provision for that. He is not going to damn us the minute we slip, like the Catholic church teaches, leaving its followers to hope that they die right after confession or communion before committing another sin.
Even in cases where there is long term sinful behavior, God will prematurely take that person before allowing them to go to hell. However, profession of a conversion experience without the resultant good works indicates that it never happened. Mere mental assent is not enough to save one. Even the demons believe and tremble. (James 2:19)
Genuine faith will result in fruit which shows up in works.
God WANTS us to be saved, which seems to be a foreign concept to most Catholics.
Calvin believed that only the elite selected from before the universe was created would be saved. Therefore it does not matter what any individual does. If selected, they cannot avoid Heaven. If not selected, they cannot avoid hell. Why would you even post something like this? If your belief system were in force, then your admonition is invalid. If it is not, then it would mean something.
An interesting thought - your belief system only means something if it is not true.