A biblical distinction is the essence of sound doctrine.
Rightly dividing the word of truth is essential if the gospel truth is to be stated clearly.
[I saw the meme here: https://www.facebook.com/ReformedChristianVoiceRadio/photos/a.714646351992461/889113734545721/?type=3&theater
It has been liked and loved 193 times, and shared 113 times when I screenshot it; if anyone has noticed the plain error, he has chosen to keep quiet.]
The statement that "a man does not become a Christian by making a decision" is wrong; it is plainly and simply wrong. To say otherwise betrays ignorance or wooliness.
Important, and sometimes costly, decisions are required for a man to become a Christian. He must decide to turn from the lies and falsehood, traditions and superstitions, and to believe the gospel of Jesus Christ that is proclaimed to him; he must decide to obey the divine command to be baptised; he must decide, with all diligence to add to his faith these... (1Pet 1:5-8). Otherwise, his profession of Christ loses all credibility.
What is true is this, "A man does not become a child of God by making a decision." To equate this statement with this "A man does not become a Christian by making a decision" betrays the wooliness and shallowness that prevails in Christendom.
A man, a regenerated man - yes, ONLY a man born of God; yes, only a child of God no less, is capable of discerning and believing the things of the Spirit (1Cor 2:14, John 3:3) - must make the momentous decision to believe the gospel of Jesus Christ and submit to believer's baptism to earn the right to bear the name of Jesus Christ, i.e. in order to become a Christian.
Cornelius was a child of God long before the gospel was brought to him by Peter; he didn't make any decision to become a child of God. His decision to believe after hearing the gospel of Jesus Christ and submitting to water baptism made him a Christian.
Regeneration and Conversion are two distinct matters.
https://things-new-and-old.blogspot.com/2017/04/rightly-dividing-regeneration-and.html