If we have faith.

 The apostles said to the Lord, "Increase our faith!"

Luke 17:5 (ESV)
 
"Men are just like the disciples. They hear religion preached; they believe the things that are said; and at times the truth glances through the exterior coating and strikes their moral sense. The ideal of truth presented to them seems beautiful and sweet. In a white light it is to them. Thousands and thousands of men there are who hear the gospel preached every Sunday, and think there is nothing more beautiful than meekness, nothing more beautiful than humility, as they are presented to them. These are excellent qualities in their estimation. They believe in love. They believe in everything that is required in a true Christian character. It meets their approval. Their reason approves it. Their judgment approves it. Their taste approves it. Their moral sentiments approve it. And yet, when they ask themselves, ‘How shall I practice it?’ they fall off instantly, and say, ‘It is not possible for me. I never can do it in the world.’”
 
"No man can change his faculties, any more than he can change his bodily organization; and yet, his disposition may be changed! The Lord says, ‘If you have faith as a grain of mustard-seed, you can say to this sycamine tree, Be thou plucked up by the roots, and cast into the sea.’ Hard as it is to transplant the tree of your soul, difficult as it is to sever the roots that hold it down, the Master says, ‘There is power to do it.’”
 
"However many faults you may have, that branch their roots out in every direction, and difficult as it is to transplant them by the ordinary instrumentalities; nevertheless, faith in the soul will give you power to pluck them up by the roots, and east them from you, or transplant them to better soil, where they will grow to a better purpose." (H. W. Beecher.)