To be "on the fence" is to be halted between two opinions. The key word here is HALT. When you cannot decide whether to follow God with all of your heart, soul, mind, and strength or whether to follow the course of this world you end up doing nothing.
2 Kings 7:3
And there were four leprous men at the entering in of the gate: and they said one to another, Why sit we here until we die?
These men had several, seemingly negative, choices they could make. They could go into the besieged city and die of famine. They could give themselves into the hands of the enemy and face the possibility of being killed. Or they could do nothing and just sit and wait to die. They decided that to sit and do nothing was the worst choice.
2 Corinthians 1:18-20
But as God is true, our word toward you was not yea and nay.
For the Son of God, Jesus Christ, Who was preached among you by us, even by me and Silvanus and Timotheus, was not yea and nay, but in him was yea,
For all the promises of God in him are yea, and in him Amen, unto the glory of God by us.
God's Word is never yes and no. ALL THE PROMISES of GOD in Christ are yea. God's Word is always YES!
I call heaven and earth to record this day against you, that I have set before you life and death, blessing and cursing: therefore choose life, that both thou and thy seed may live:
There is no middle ground as far as God is concerned. God sets forth His Word in black and white terms. Here is life. Here is death. Choose life. He tells us the two choices and He also tells us which one is the correct one. But man, having freedom of will, must do the choosing. To often we find ourselves halted between two opinions. Yes - No, Yes - No. "On the fence" is a heart rending place to be.
Now therefore fear the LORD, and serve him in sincerity and in truth: and put away the gods which your fathers served on the other side of the flood, and in Egypt; and serve ye the LORD.
And if it seem evil unto you to serve the LORD, choose you this day whom ye will serve; whether the gods which your fathers served that were on the other side of the flood, or the gods of the Amorites, in whose land ye dwell: but as for me and my house, we will serve the LORD.
Although the Children of Israel walked mightily with Joshua and took possession of the promised land, they still tried to "have it both ways." Before Joshua died he challenged them to choose. Serve God or serve the gods of this world. Make a decision. Take a stand. The choice for Joshua was clear: "As for me and my house, we will serve the LORD!"
In truth, there is no middle ground. If you are not serving the true God then you are locked into the course of this world. The real problem is your heart. "On the fence" you are torn inside between giving your all for God or setting God aside and walking the course of the world. You cannot do both, so why not give your all for God?
No man can serve two masters: for he will hate the one, and love the other; or else he will hold to the one, and despise the other. Ye cannot serve God and mammon.
Mammon are worldly things. In the context, treasures on earth are thoughts about food, clothing, housing, and riches. Fears and worries about these worldly things steal your heart. In contrast, treasures in heaven are thoughts centered on God. When your heart is clearly focused on God, then He takes care of your worldly needs.
But seek ye first the kingdom of God, and his righteousness; and all these things shall be added unto you.
Give your all: your heart, soul, mind, and strength to serving God and He has promised to take care of the rest. God's Word is simple. Trust Him.
If any of you lack wisdom, let him ask of God, that giveth to all men liberally, and upbraideth not; and it shall be given him.
But let him ask in faith, nothing wavering. For he that wavereth is like a wave of the sea driven with the wind and tossed.
For let not that man think that he shall receive any thing of the Lord.
A double minded man is unstable in all his ways.
God's promises are ALL YEA! There is no variance with God. Ask Him what to do and will give you the answer liberally (without a second thought!) God does not upbraid: He does not reprove you for not already knowing what to do. The simplicity of the Word is: Ask God what to do and God will absolutely give you an answer. The key is to completely trust God. When you waver between two opinions: yes - no, yes - no, God's Word says you are driven like a wave of the sea: back and forth, back and forth. When you sit on the fence between believing and not believing you receive nothing. A double minded man is unstable in all his ways.
Ye ask, and receive not, because ye ask amiss, that ye may consume it upon your lusts.
Ye adulterers and adulteresses, know ye not that the friendship of the world is enmity with God? whosoever therefore will be a friend of the world is the enemy of God.
Do ye think that the scripture saith in vain, The spirit that dwelleth in us lusteth to envy?
But he giveth more grace. Wherefore he saith, God resisteth the proud, but giveth grace to the humble.
Submit yourselves therefore to God. Resist the devil, and he will flee from you.
Draw nigh to God, and he will draw nigh to you. Cleanse your hands, ye sinners; and purify your hearts, ye double minded.
You cannot be friend of the world and also be God centered. It is pride to think that you can. The Devil holds many captive: halted between two opinions. You resist the Devil by drawing nigh to God. Submit yourself to God and the Devil will flee. A pure heart is not double minded.
I know thy works, that thou art neither cold nor hot: I would thou wert cold or hot.
So then because thou art lukewarm, and neither cold nor hot, I will spue thee out of my mouth.
To be "on the fence" is to halt between two opinions, to say both yea and nay to God's Word, to try to serve God and mammon, to be double minded, to be lukewarm. Why sit we here on the fence until we die? Let us say with Joshua: "As for me and my house, we will serve the LORD!"
Let us hear the conclusion of the whole matter: Fear God, and keep his commandments: for this is the whole duty of man.