A person wrote to Billy Graham stating they were tempted to do something they knew was wrong. They asked if it mattered whether they gave in to this temptation because God has promised to forgive our sins. 
This question essentially views Christianity as a “get out of jail (hell) free” card. It is not an unusual way of looking at Christianity because the apostle Paul faced the same question.
The law was added so that the trespass might increase. But where sin increased, grace increased all the more, so that, just as sin reigned in death, so also grace might reign through righteousness to bring eternal life through Jesus Christ our Lord.
What shall we say, then? Shall we go on sinning so that grace may increase? By no means! We died to sin; how can we live in it any longer? Or don’t you know that all of us who were baptized into Christ Jesus were baptized into his death? We were therefore buried with him through baptism into death in order that, just as Christ was raised from the dead through the glory of the Father, we too may live a new life. (Romans 5:20-6:4 NIV)
In the above passage Paul states that Christ’s work on our behalf includes his death for our sins but also his resurrection so that we can live a new life. This new life is just as much a part of salvation as Jesus’ death for our sins. If our doctrine of salvation made this plain instead of stating that salvation is through belief in Jesus alone, then we might see fewer people trying to use Christianity as a “get out of jail free” card.
 Billy Graham, “God will forgive every sin except one”, Tulsa Beacon, February 4, 2016, p. 2B.