Because we have to, because we need to, or because we want to. We could add because we have been told to, but just because we have been commanded to, does not mean we have to obey.
“Whether therefore ye eat, or drink, or whatsoever ye do, do all to the glory of God.” (1st Cor. 10:31)
The choice of free will has nothing to do with having to or needing to, in fact, those two are so closely related that they could be placed together, the only reason we have to do anything is because it needs to be done, and even that can be a choice at times.
Except for the continuation of the flesh my friends, in all reality everything we do we do because we want to, there are very few alternatives to this truth. One can of course be forced to do something, but the mind in that regard can still deny that external action of force, ask anyone who has done prison time about this truth.
“And thou shalt love the Lord thy God with all thy heart, and with all thy soul, and with all thy mind, and with all thy strength: this is the first commandment.” (Mark 12:30)
“And the second is like unto it, Thou shalt love thy neighbour as thyself.” (Matt. 22:39)
These may be commandments, but they cannot be forced on anyone, love is always a choice.
“If ye love me, keep my commandments.” (John 14:15)
Obedience out of love for the Lord Jesus Christ, without any thoughts to ourselves, is a sure sign of salvation, if it is a “want to,” an action performed by the desire of our heart. Those who believe we must follow some part of the Levitical, Mosaic, or Ten Commandment Laws do not understand this truth, those who believe in the necessity of some form of works not only towards their salvation but as proof of it, do not understand “want to,” they still believe they “need to.”
“For by grace are ye saved through faith; and that not of yourselves: it is the gift of God: Not of works, lest any man should boast.” (Eph. 2:8-9)
This letter could end right here, for these truths are self-evident throughout the entire Word of God, grace requires no works from us, and obedience offered because of love produced by faith in the truths of the Scriptures reveals that needing to has never been the way of our Lord toward us, if we do not want to, He does not force us to.
“For I have not spoken of myself; but the Father which sent me, he gave me a commandment, what I should say, and what I should speak.” (John 12:49)
You must remember this, and apply it to all that is written here, the Lord Jesus Christ did not have to be born of a woman, He did not need to live a life of grief and sorrow, He wanted to please the Father, and so He went to the cross, He drank the cup set before Him of His own free will.
“Saying, Father, if thou be willing, remove this cup from me: nevertheless not my will, but thine, be done.” (Luke 22:42)
No one has to serve the Almighty, in all reality, no one needs to, there will be dire and eternal consequences if they do not, but if they do not want to obey Him, if they decide they would rather live their lives apart from Him, if that is what they want to do, that is what He will let them do.
All this boils down to one question, do you honestly want to serve the Lord, no matter the way He calls you to, no matter the consequences to yourself, or do you still harbor certain thoughts of needing to do something to remain pleasing in His eyes?
Do you feel you have to, that you need to, or do you really want to?
Our free will determines just how much we are willing to submit of ourselves for His glory, there is nothing but wanting to in this truth. You were called, you were chosen, and then you were given a choice, “How much of yourself are you willing to give to Me?”
“I am crucified with Christ: nevertheless I live; yet not I, but Christ liveth in me: and the life which I now live in the flesh I live by the faith of the Son of God, who loved me, and gave himself for me.” (Gal. 2:20)
I am not really sure that any of us can give ourselves fully over to His will, no matter how much we may want to, our flesh, our old nature will remain a part of us until we are glorified. But when the Almighty sees within us a sincere heart that wants to, then the true needs begin to fall in place.