Those calling themselves Christian but who endorse or practice homosexual relationships, same-sex marriages, transgenderism, cross-dressing and sexual relationships outside of marriage between a man and a woman haven’t read and accepted the clear teaching of the Bible.
Look up what God says in His Word and see for yourself: Genesis 1:26-27; 2:18-25; 18:16 — 19:29; Leviticus 18:1-30; 20:1-23; Deuteronomy 22:5; Matthew 5:27-32; 19:3-9; Romans 1:18-32; 1 Corinthians 6:9-11; Galatians 5:19-21; Ephesians 5:3-5; Jude 5-7; Revelation 21:8.
Rather than pretending to be Christian, those who endorse practicing what God calls sin should be honest and simply acknowledge that they do not accept the Bible and the teaching of Christ and His apostles. To do otherwise is hypocrisy and self-deception.
The Bible warns against these and other sins that we all might examine ourselves, repent of our sins and look to Christ Jesus and His cross for pardon and forgiveness and then seek to amend our evil ways and live for our God and Savior in accord with His holy Word (cf. Luke 24:46-47; Acts 3:19; 2 Peter 3:9; Psalm 32; Psalm 139:23-24; Isaiah 55:6-7). To do otherwise is the opposite of being Christian.