How do you know if you're really a Christian? This can be a dangerous question if taken the wrong way, so you have to check your intentions (not asking as a means to judge others or to beat yourself up for an area in which you think you fall short).
At the same time there's a concerning trend: There are far too many people who think that they are Christians, but aren’t actually in Christ. We have a genuine love and concern for those in the church who may assume salvation is by association. Are we depending on church attendance, family background, and good intentions?
Genuine faith shows evidence of regeneration. Scripture gives us five criteria by which you can evaluate faith. If these things are present in your life, they are indications that you are truly being transformed by a vibrant and real faith.
Belief in true doctrine. You aren't a Christian if you simply like Jesus. Lots of people like Jesus. Gandhi wrote fondly of Jesus' gentleness, the Dalai Lama applauded him as "enlightened," and most people enjoy seeing his face around Christmastime sprinkled somewhere in the commercial jungle. To be a genuine Christian, you must have sincere faith in Christ and his atoning work on the cross. That must be the central drive of your life. (Rom 16:17-18; Eph 4:11-16; 1Tim 4:6-8; 1Tim 6:3-5; Titus 1:9)
Hatred of sin in your life. All Christians struggle with sin. But if you have real faith, you will not enjoy your sins, but work to stamp them out. We all sin, Christians and non-Christians alike. The difference lies in the the effort and desire to improve ourselves and sin less vs. allowing sinful practices to be the enjoyable, ongoing trajectory of our lives. (Psalm 38:18, 119:11; Mark 9:42-47; John 8:11; Rom 6:1-2, 11-18; 1Tim 5:20; Heb 12:1-4; 1John 3:9-10)
Perseverance over time. You're not a Christian if you don't persevere in your faith and endure through the spiritually dark times. God is certainly there to sustain you, but you are also responsible for making the conscious, and sometimes painful, effort to endure in the faith. (Col 1:21-23; 2Tim 3:14-15; John 15:4-11; 2John 1:9; Heb 3:13-14)
Love for other people. Genuine Christians have care and concern for other people. This includes brothers and sisters in the faith, the poor and downtrodden, and, hard as it is, your enemies. (Matt 22:36-40; Luke 6:35; John 13:34-35, 15:12-13; Rom 12:9-10; Gal 5:13-14; Heb 13:1-3; 1John 2:9-10, 3:17)
Freedom from love of the world. You aren't a Christian if the things of this world are more valuable to you than your faith in God. Prosperity is not inherently bad, and it can be evidence of obedience and wisdom. But it is tremendously easy for those with wealth to rely on money more than God. Money has an uncanny power of numbing peoples' need for the Lord. Only God can meet your greatest needs. (Matt 16:24-26; Mark 4:2-20; Luke 14:25-33; Rom 12:2; Gal 4:3-9; Heb 13:5; 1John 2:15)
Adapted from Am I Really a Christian? by Mike McKinley.