Or must you believe on his name? I read the KJV and have trouble with this. At the end of the Gospel According to John it says that the signs written about are there so that you might believe that Jesus is the Christ, the Son of God, and that believing you might have life through his name. The reading can be tricky unless I'm just being very careful about it, but it seems along with what is written about in John 3 it might be necessary to believe on his name, ie. it's not enough to just believe in Jesus. I think this is important. I also think this subject is important for recognizing that the KJV is the Holy Bible to be read as it's the most reasonable (the standard red letter edition, in my opinion) and if you believed through another Bible you might not actually be believing on his name since something could be changed.
2Ti 2:19 Nevertheless the foundation of God standeth sure, having this seal, The Lord knoweth them that are his. And, Let every one that nameth the name of Christ depart from iniquity.
Mat 7:21 Not every one that saith unto me, Lord, Lord, shall enter into the kingdom of heaven; but he that doeth the will of my Father which is in heaven.
Mat 7:23 And then will I profess unto them, I never knew you: depart from me, ye that work iniquity.
Joh 14:23 Jesus answered and said unto him, If a man love me, he will keep my words: and my Father will love him, and we will come unto him, and make our abode with him.
Joh 14:24 He that loveth me not keepeth not my sayings: and the word which ye hear is not mine, but the Father's which sent me.
2Ti 3:4 lovers of pleasures more than lovers of God;
2Ti 3:5 Having a form of godliness, but denying the power thereof: from such turn away.
2Ti 3:7 Ever learning, and never able to come to the knowledge of the truth.
Gal 5:16 This I say then, Walk in the Spirit, and ye shall not fulfil the lust of the flesh.
Gal 5:22 But the fruit of the Spirit is love, joy, peace, longsuffering, gentleness, goodness, faith,
Gal 5:23 Meekness, temperance: against such there is no law.
Gal 5:24 And they that are Christ's have crucified the flesh with the affections and lusts.
Gal 5:25 If we live in the Spirit, let us also walk in the Spirit.
1Co 10:12 Wherefore let him that thinketh he standeth take heed lest he fall.
1Co 10:13 There hath no temptation taken you but such as is common to man: but God is faithful, who will not suffer you to be tempted above that ye are able; but will with the temptation also make a way to escape, that ye may be able to bear it.
To believe in Jesus is to know the truth to abstain from sin.
Many people do not do that.