As we are living under the Grace of our Lord Jesus Christ, much more is required. We are to give over and above the tithe, so it could be 15%, 20%, or even 50% depending on how much we feel blessed to give, considering 100% belongs to the Lord and without His blessings, we'd have nothing.
Giving from the heart shows that we have the heart of Jesus. However, you can’t put a percentage on it and there are many ways to give back beyond writing a check. We should also give of our talents, time, energy, and attention to further his kingdom.
I will tell anyone who will listen to BEWARE of any church or pastor that seems fixated on your wallet and there is no magical number as a percentage that demonstrates our walk.
Every Christian should contemplate the lesson of the widow’s mite. Was Christ celebrating a poor woman who gave everything, was he rebuking the hypocrisy of the temple/priests that were supposed to care for her (not take from her), or was it both?
The answer to this question (individually) reveals our understanding of the heart of Christ. I believe it is an important question for each Christian to answer and study.
Any pastor who preaches this story while beating you over the head about tithing has missed the beautiful lesson straight from Jesus that best reflects his heart for giving. That is a pastor who is perverting the scripture for his own gain. Strong statement, but that is my opinion.