Dear friends, if our hearts do not condemn us, we have confidence before God
NIV
And, beloved, if our consciences (our hearts) do not accuse us [if they do not make us feel guilty and condemn us], we have confidence (complete assurance and boldness) before God
AMP
Beloved, if our heart condemn us not, then have we confidence toward God.
KJV
I am writing to you, fathers, because you know him who is from the beginning. I am writing to you, young people, because you have overcome the evil one.
NIV
I am writing to you, fathers, because you have come to know (recognize, be aware of, and understand) Him Who [has existed] from the beginning. I am writing to you, young men, because you have been victorious over the wicked [one]. I write to you, boys (lads), because you have come to know (recognize and be aware) of the Father.
AMP
I write unto you, fathers, because ye have known him that is from the beginning. I write unto you, young men, because ye have overcome the wicked one. I write unto you, little children, because ye have known the Father.
KJV