Clarifying 2 Timothy 2:13

2 Timothy 2:13 says, "If we believe not, yet He abideth faithful: He cannot deny Himself."

Does that mean there's such a thing as an ex-believer and that ex-believers are still saved?  Well, first there may be such a thing as a backslid Christian, a Christian having issues with carnality and all that but there is NO ex-believer (1 John 2:19), that is once saved always saved is manifested by the fact that Christians do not depart from the faith in contrast to those fake believers and the lifestyles of a saved person will be shown.  Christians will always be Christians and never cease from being Christians.  To look at the verse correctly, believing here does not refer to trusting in Christ.  A Christian can have certain doubts about their Christian life especially whether or not they are saved as Satan just loves to throw darts of discouragement at them.  Yet in the process, God still continues to preserve the believers even when they are in doubt and as a result, their doubts can be cured all thanks to the work of the Holy Spirit.  As said, Christians are not only saved but they are also sanctified and justified resulting to good works that are a result of salvation.