Oyster,
Belief is a part of being with Christ. Logicly one must believe in the exsistance of Christ before they can or will commit to following Him. No one follows or makes a commitment to anything that they don't or can't believe.
There are two kinds of belief when it comes to Christ Jesus.
The first is (What I call) an academic belief.
One can study the bible and reason to understand and believe the exsistance of Jesus as well as all or most of what is said about Him. But this is a detached belief, as in we can know about anyone we study or read about. Example George Washington, Nero, Shakespere, etc. We can know about them and believe in their existance even though we will never make a personal contact with them.
Then there is a kind of belief fostered by a personal relationship with that person. Like a parent ,family, freind or child. This kind of belief can be had with Jesus as well. It is a much much deeper and intimate relationship that brings with it a belief and understanding that is of the heart. One that makes it possible to see Him in the people and things around us. Understand His thoughts in the words of scripture and hear His voice in the words spoken to us by others.
The signs of this kind of relationship and belief are not found in performance of wonders or miracles, but in our own hearts and experiences with Him.
Do not be concerned that you do not the things man says are actions of believers. Men can only read the actions, God reads the heart.
Mar 16:14 Afterward he appeared unto the eleven as they sat at meat, and upbraided them with their unbelief and hardness of heart, because they believed not them which had seen him after he was risen.
Mar 16:15 And he said unto them, Go ye into all the world, and preach the gospel to every creature.
Mar 16:16 He that believeth and is baptized shall be saved; but he that believeth not shall be damned.
Mar 16:17 And these signs shall follow them that believe; In my name shall they cast out devils; they shall speak with new tongues;
Mar 16:18 They shall take up serpents; and if they drink any deadly thing, it shall not hurt them; they shall lay hands on the sick, and they shall recover.
Mar 16:19 So then after the Lord had spoken unto them, he was received up into heaven, and sat on the right hand of God.
Mar 16:20 And they went forth, and preached every where, the Lord working with them, and confirming the word with signs following. Amen.
In context, Mark 16:14-20 is Jesus' last instructions and encouragment to the remaining Apostiles to go forth and spread the Gospel. He was letting them know ,first that they were protected against evil and that they had power and authority to do what they had been given to do.
These things do not always apply in our lives today. That's not to say that God doesn't protect us or prepare us for works in His Holy Name. But that the protection and preperation does not necessarily involve any or all of the things mentioned in preceeding verses.
Therefore, they are not reliable signs of belief or salvation and though many times they are, should not be used as such.
All gifts and signs are of the Holy Spirit and as such are at the control of the Holy Spirit for God's purpose. Any believer may manifest some or none of these signs simply because it does suits the purpose of God for them to.
The more reliable signs are :
A defining moment; A point in time when realizes that they are because of mans nature sinful and in no way can with out Jesus redeem themselves. Were upon they confess their sins (before God) repent(make a sincere effert to correct and turn around their life)accept Jesus as Lord(commit to follow the example of and obey Jesus).
A sustained effert: For the believer this is a heart felt conviction or compulsion to learn, understand and live a life dedicated to Jesus as LORD.
To the world this change and effert often goes unseen. To those close to us it is most evident. But the signs are not demonstrated in wonders and miracles but most often in a change in life style and attitude tward God and others.
Joh 13:35 By this shall all men know that ye are my disciples, if ye have love one to another.
Joh 13:34 A new commandment I give unto you, That ye love one another; as I have loved you, that ye also love one another.
Joh 14:15 If ye love me, keep my commandments.