“Let us hold fast the confession of our hope without wavering, for He who promised is faithful.” Hebrews 10:23
What causes a believer walking with God to waver in his faith?

The cause will always relate to fear or doubt. Something has happened in your world to cause you to doubt God.
In actuality, you have brought this doubt upon yourself because you are judging God by the standards of the world and not by His Word.
God does not function according to the world. In fact, He died to overcome the world. As a believer, you and I live in the world but we are not of the world.
So when the trials of life come upon you what is vitally important is to operate under the promises of God and give no power to your feelings which will always lead you astray from God.
Your feelings have no power to change your life but the Holy Spirit living within you can overcome your feelings and do a powerful work to restore your faith in the Living Christ.
Come to God by faith living in this precious promise from your Creator; “Now to Him who is able to do exceedingly and abundantly more than you ask or think according to the power working within you.”
When your ship is seeking turn to Christ Jesus who can steady your vessel. And, He will give you more than you could ever imagine!