Question:
If someone is saved, is it possible for them to fall so far away from the Lord as to murder or do something as horrible as that? If that is possible, the Lord would understand and forgive—right?

Answer:
Yes, it is possible for a believer to do as horrible a thing as even the most wicked person is capable of doing. It is correct, also, that the Lord forgives the most horrible things. But more must be said about this because of the gravity of such things.

Sin in the believer is just as wicked as sin in the most ungodly person. But, in Christ, our God has given us power over sin. Believers have been delivered from the bondage of sin; the ungodly have not. It is most heinous for the believer to do such things. If one does, we can be certain that God’s judgment will be upon that one in this life so as not to be condemned with the world (see 1 Corinthians 11:31, 32). Remember how God dealt with king David concerning the death of Uriah the Hittite in the Old Testament. God’s holy discipline in the lives of believers is certain and sure. It is for our profit, that we might be partakers of His holiness (Hebrews 12:10). If we live closely to the Lord, we will not do such things.
Next, it is most important to see that it is the blood of our Lord Jesus Christ that cleanses us from every sin (1 John 1:7). Every sin! We stand accepted, complete and without sin in virtue of the blood of Christ. Our God, more than anyone, understands what sin is and that only the blood of Christ can remove all guilt. After all, He is the One who provided for our eternal salvation.
But remember, there is not a more miserable person living on the face of the earth than a believer who is living carelessly before the Father concerning his daily life. This also takes in the “lesser” sins that we sometimes brush off as being “not all that serious.” Our God hates ALL KINDS of sin. May it be in our hearts, then, to walk in obedience according to His Word so that we may enjoy constant fellowship with the Father and the Son.