The Inner Being Issue - Only Yourself can answer.
A true Christ-Believer is someone who know, believe that Jesus is the Son of God and has a relationship with Him.
John 3:16 tells us "For God so loved the world that he gave his one and only Son, that whoever believes in him shall not perish but have eternal life."
We need to know first before we can believe. So I put know before believe. v16 tells us to know that Jesus is the one and only Son sent from God.
This is repeated in Jesus' prayer to His Father God in John 17:3
"And this is eternal life, that they know you the only true God, and Jesus Christ whom you have sent."
We need to understand another term well "eternal life". Eternal life is not just about never ending life. This is because everyone has a never ending life anyway. When the physical body died, the spirit and the soul of man continue to exist. The more important question is the where does the after death spirit go? To hell with the devils or to heaven with God and angels? So the eternal-life should mean more than just eternal but life with God. Hebrew word eternal is olam meaning more than long-time but as the horizon beyond, another dimension of life, the heavenly life of God. To have most intimate relationship, we must be of the same kind. Man can have a good relationship with dog. But man can have a higher and more intimate relationship with man/women(wife). Man have a good relationship with God since we are created in the image of God. But man can have intimate relationship with God when man is rebirthed by the Holy Spirit of God into the same form of life as God and live as children of God.
Of course, one shouldn't just stop at knowing Jesus as Son of God. We would like to know more of Him and to talk with Him so that we can have a on going and real life relationship with Him.
When we are rebirthed by the Holy Spirit, we took upon Jesus' righteousness and we are pure and clean. Our conscience becomes very sensitive and sharp and some things in the past that we used to think are ok are now not ok! Our new identity will naturally be uncomfortable with sins and evil. However, our spirit is new born but our mind and our body remain as before. We need to grow up in spiritual maturity to control our mind and body.
Not Just the Sinners' Prayer
Most of us judge whether another is a born-again Christian by asking them whether they have prayed the sinner prayer (the most simplified form is: Jesus, I believed you as the Son of God who died for my sins. I confessed that I am a sinner. I received you as by Savior and Lord. Amen.). But such is not the requirement of John 3:16. The 'sinner's prayer' of the thief at the cross with Jesus is ""Jesus, remember me when you come into your kingdom." Luke 23:42 and Jesus' response was most immediate, " Luke 23:43 Jesus answered him, "I tell you the truth, today you will be with me in paradise." The key to salvation and rebirth is not about confessing your sins but about knowing Jesus as from and is God and acknowledging Him as our God.
There are people who just merely say out the sinner's prayer to get rid of such pushy Christians or to satisfy their girl-friend's requirement for being a Christian first before marriage. So we cant tell whether a person is truly a Christian or not by what he say or claim. Only God and him can truly know.
Nevertheless, Believers must exhibit Believers' Behavior.
9 “As the Father has loved me, so have I loved you. Now remain in my love. 10 If you keep my commands, you will remain in my love, just as I have kept my Father’s commands and remain in his love.
Please remember that we are born anew as a spiritual baby and baby needs to take good spiritual food, exercise and love to grow up. Give yourself time to grow up. Find good fellow believers for fellowship. Even Paul went through tough struggles as in Rom 7. But the secret weapon is to abide in the love of Jesus Christ. Spend time to know and be loved by Him. We get to know Him more also by moving out in obedience and taking on challenging tasks to taste that His grace is sufficient resulting in increasing trust and obedience.
For details on growth see ...Christian Transformation & Growth -The Unified Model
May we all grow up in maturity into the image of Christ. Rom 8:29.