The gospel according to Matthew tells of the moment when Jesus talked with His disciples and taught them about faith.
Many people think faith is not necessary but the Bible itself teaches that without faith and love we cannot please God, but we see that the first thing that was mentioned was faith, since faith is what allows us to believe in the Lord with all our heart, helps us every day to trust in God and to believe that some day what we all have long awaited will be manifested: The coming of our beloved Lord Jesus Christ.
Faith in the Lord is what keeps us standing, it allows us to look for Him day by day. It helps us to pass those trials that come every day to scourge our spirit so that we faint and stop believing in the Lord.
And Jesus said unto them, Because of your unbelief: for verily I say unto you, If ye have faith as a grain of mustard seed, ye shall say unto this mountain, Remove hence to yonder place; and it shall remove; and nothing shall be impossible unto you.
In the previous verse Jesus tells His disciples clearly that with a little faith they can do great things. We can clearly see that faith in the Lord is so powerful that it will help us move everything that wants to trouble us in the Lord. All walls that are laid will be torn down, we can resist all trials in the Lord because we faithfully believe in Him. That is why we pray every day for God to increase our faith. Remember that nothing is impossible for Him.