To all who believed him and accepted him, he gave the right to become children of God.
John 1:12 NLT

God's fatherhood
Most people in the world would agree with the statement that "we are all God's children."
It's a nice sentiment.
It just isn't what the Bible teaches.
According to God's Word, unrepentant sinners are actually God's enemies (see Romans 5:10 and Colossians 1:21)!
It's only when we put our trust in the Lord Jesus Christ that we are reconciled to God and experience forgiveness and adoption into God's forever family (Galatians 4:5; Ephesians 1:5).
For a Christian going through hard times, this "adoption" truth is the best of all possible news.
God is not just the powerful Creator or a righteous Lord, he is a loving Father.
He sees your trials.
He listens to your pleas.
He cares and protects and supports.
He is never harsh or impatient with you.
He is never "too busy" for you.
Take all the best qualities of all the best earthly dads you've ever seen, add them together, and multiply by infinity. That's the kind of heavenly Father God is to Christians who hurt.

Lord Jesus, I do believe in you. I have accepted you as my Savior and Lord. Thank you for revealing yourself to me. Thank you for saving me! Because of your grace and my faith, I am a child of the living God. I praise you. What a privilege! What joy to know that in every situation I have a loving, wise, and good heavenly Father to counsel and help me.

adapted from Praying God's Promises in Tough Times by Len Woods, Tyndale House Publishers (2002), pp 68-9